(CNN) Republican donors who are still willing to give to Donald Trump are increasingly uneasy -- not just about the constant controversy surrounding the presumptive GOP nominee but also the perceived total lack of infrastructure related to his nascent fundraising operation.

The list of problems, according to donors and party officials, is both long and not easy to fix over the course of a short period.

In many ways, it's only natural. Trump rolled through the primary haranguing the donor community, including some of the party's top money men and women by name, as he pledged to self-fund his campaign. Some notable top donors, including financier Paul Singer and Joe and Marlene Ricketts, are sitting out the campaign.

But interviews with more than a dozen donors, party, campaign and congressional officials make clear the concerns have moved beyond bruised feelings over personal slights -- and even beyond the top donors who simply won't give to the New York billionaire.

"This isn't a triage-type of situation," said one GOP donor who backed Jeb Bush during the primary, but is planning to give to Trump. "This is a massive, full body surgery type deal and we just don't have much time for that."

The anxiety is unfolding as a faction of Republicans is pinning a last-ditch effort to stop Trump at next month's GOP convention. Trump himself doesn't seem concerned, insisting he can fund his own campaign if the GOP doesn't get in line.

Over the weekend, Trump didn't seem to worried about the concerns surrounding his operation, insisting he can self-fund his campaign.

"If for any reason they get a little bit like they don't want to help out as much, I'll fund my own campaign," he said at a rally Saturday. "I'd love to do that."

Major shakeup

But a major shakeup was underway Monday as Trump ousted campaign manager Corey Lewandowski

Photos: Donald Trump's rise Photos: Donald Trump's rise President-elect Donald Trump has been in the spotlight for years. From developing real estate and producing and starring in TV shows, he became a celebrity long before winning the White House. Hide Caption 1 of 37 Photos: Donald Trump's rise Trump at age 4. He was born in 1946 to Fred and Mary Trump in New York City. His father was a real estate developer. Hide Caption 2 of 37 Photos: Donald Trump's rise Trump, left, in a family photo. He was the second-youngest of five children. Hide Caption 3 of 37 Photos: Donald Trump's rise Trump, center, stands at attention during his senior year at the New York Military Academy in 1964. Hide Caption 4 of 37 Photos: Donald Trump's rise Trump, center, wears a baseball uniform at the New York Military Academy in 1964. After he graduated from the boarding school, he went to college. He started at Fordham University before transferring and later graduating from the Wharton School, the University of Pennsylvania's business school. Hide Caption 5 of 37 Photos: Donald Trump's rise Trump stands with Alfred Eisenpreis, New York's economic development administrator, in 1976 while they look at a sketch of a new 1,400-room renovation project of the Commodore Hotel. After graduating college in 1968, Trump worked with his father on developments in Queens and Brooklyn before purchasing or building multiple properties in New York and Atlantic City, New Jersey. Those properties included Trump Tower in New York and Trump Plaza and multiple casinos in Atlantic City. Hide Caption 6 of 37 Photos: Donald Trump's rise Trump attends an event to mark the start of construction of the New York Convention Center in 1979. Hide Caption 7 of 37 Photos: Donald Trump's rise Trump wears a hard hat at the Trump Tower construction site in New York in 1980. Hide Caption 8 of 37 Photos: Donald Trump's rise Trump was married to Ivana Zelnicek Trump from 1977 to 1990, when they divorced. They had three children together: Donald Jr., Ivanka and Eric. Hide Caption 9 of 37 Photos: Donald Trump's rise The Trump family, circa 1986. Hide Caption 10 of 37 Photos: Donald Trump's rise Trump uses his personal helicopter to get around New York in 1987. Hide Caption 11 of 37 Photos: Donald Trump's rise Trump stands in the atrium of the Trump Tower. Hide Caption 12 of 37 Photos: Donald Trump's rise Trump attends the opening of his new Atlantic City casino, the Taj Mahal, in 1989. Hide Caption 13 of 37 Photos: Donald Trump's rise Trump signs his second book, "Trump: Surviving at the Top," in 1990. Trump has published at least 16 other books, including "The Art of the Deal" and "The America We Deserve." Hide Caption 14 of 37 Photos: Donald Trump's rise Trump and singer Michael Jackson pose for a photo before traveling to visit Ryan White, a young child with AIDS, in 1990. Hide Caption 15 of 37 Photos: Donald Trump's rise Trump dips his second wife, Marla Maples, after the couple married in a private ceremony in New York in December 1993. The couple divorced in 1999 and had one daughter together, Tiffany. Hide Caption 16 of 37 Photos: Donald Trump's rise Trump putts a golf ball in his New York office in 1998. Hide Caption 17 of 37 Photos: Donald Trump's rise An advertisement for the television show "The Apprentice" hangs at Trump Tower in 2004. The show launched in January of that year. In January 2008, the show returned as "Celebrity Apprentice." Hide Caption 18 of 37 Photos: Donald Trump's rise A 12-inch talking Trump doll is on display at a toy store in New York in September 2004. Hide Caption 19 of 37 Photos: Donald Trump's rise Trump attends a news conference in 2005 that announced the establishment of Trump University. From 2005 until it closed in 2010, Trump University had about 10,000 people sign up for a program that promised success in real estate. Three separate lawsuits -- two class-action suits filed in California and one filed by New York's attorney general -- argued that the program was mired in fraud and deception. Trump's camp rejected the suits' claims as "baseless." And Trump has charged that the New York case against him is politically motivated. Hide Caption 20 of 37 Photos: Donald Trump's rise Trump attends the U.S. Open tennis tournament with his third wife, Melania Knauss-Trump, and their son, Barron, in 2006. Trump and Knauss married in 2005. Hide Caption 21 of 37 Photos: Donald Trump's rise Trump wrestles with "Stone Cold" Steve Austin at WrestleMania in 2007. Trump has close ties with the WWE and its CEO, Vince McMahon. Hide Caption 22 of 37 Photos: Donald Trump's rise For "The Apprentice," Trump was honored with a star on the Hollywood Walk of Fame in January 2007. Hide Caption 23 of 37 Photos: Donald Trump's rise Trump appears on the set of "The Celebrity Apprentice" with two of his children -- Donald Jr. and Ivanka -- in 2009. Hide Caption 24 of 37 Photos: Donald Trump's rise Trump poses with Miss Universe contestants in 2011. Trump had been executive producer of the Miss Universe, Miss USA and Miss Teen USA pageants since 1996. Hide Caption 25 of 37 Photos: Donald Trump's rise In 2012, Trump announces his endorsement of Republican presidential candidate Mitt Romney. Hide Caption 26 of 37 Photos: Donald Trump's rise Trump speaks in Sarasota, Florida, after accepting the Statesman of the Year Award at the Sarasota GOP dinner in August 2012. It was shortly before the Republican National Convention in nearby Tampa. Hide Caption 27 of 37 Photos: Donald Trump's rise Trump appears on stage with singer Nick Jonas and television personality Giuliana Rancic during the 2013 Miss USA pageant. Hide Caption 28 of 37 Photos: Donald Trump's rise In June 2015, during a speech from Trump Tower, Trump announced that he was running for President. He said he would give up "The Apprentice" to run. Hide Caption 29 of 37 Photos: Donald Trump's rise Trump -- flanked by U.S. Sens. Marco Rubio, left, and Ted Cruz -- speaks during a CNN debate in Miami on March 10. Trump dominated the GOP primaries and emerged as the presumptive nominee in May. Hide Caption 30 of 37 Photos: Donald Trump's rise The Trump family poses for a photo in New York in April. Hide Caption 31 of 37 Photos: Donald Trump's rise Trump speaks during a campaign event in Evansville, Indiana, on April 28. After Trump won the Indiana primary, his last two competitors dropped out of the GOP race. Hide Caption 32 of 37 Photos: Donald Trump's rise Trump delivers a speech at the Republican National Convention in July, accepting the party's nomination for President. "I have had a truly great life in business," he said. "But now, my sole and exclusive mission is to go to work for our country -- to go to work for you. It's time to deliver a victory for the American people." Hide Caption 33 of 37 Photos: Donald Trump's rise Trump faces Democratic nominee Hillary Clinton in the first presidential debate, which took place in Hempstead, New York, in September. Hide Caption 34 of 37 Photos: Donald Trump's rise Trump apologizes in a video, posted to his Twitter account in October, for vulgar and sexually aggressive remarks he made a decade ago regarding women. "I said it, I was wrong and I apologize," Trump said, referring to lewd comments he made during a previously unaired taping of "Access Hollywood." Multiple Republican leaders rescinded their endorsements of Trump after the footage was released. Hide Caption 35 of 37 Photos: Donald Trump's rise Trump walks on stage with his family after he was declared the election winner on November 9. "Ours was not a campaign, but rather, an incredible and great movement," he told his supporters in New York. Hide Caption 36 of 37 Photos: Donald Trump's rise Trump is joined by his family as he is sworn in as President on January 20. Hide Caption 37 of 37

Trump has ramped up his fundraising efforts in a recent swing through Texas and he had a helping hand by his side -- RNC Chairman Reince Priebus (who one donor called "the most goddamn persistent fundraiser I've ever met.") His almost non-existent operation has received a significant boost from a joint fundraising agreement signed with the RNC -- with it comes an at-the-ready donor and digital infrastructure. The dividends of that were clear on Saturday, as the RNC's digital operation fired out an e-mail with the title "Crooked Hillary drops $7 million in attack ads" that sought to meet an "emergency goal" of $100,000 in one day.

Yet the RNC agreement also brought old tensions between Trump's team and the party apparatus back to the surface. Distrust -- or, according to one official, general confusion inside Trump's team -- over how the joint-fundraising committee actually works (and who benefits most -- Trump or the RNC) has riled an already unsteady relationship between the two entities.

Priebus shot down the persistent talk of problems on Twitter Thursday as he flew to Texas with Trump, noting that "reports of discord are pure fiction. Great events lined up all over Texas." Trump, helpfully, retweeted the tweet.

Flying to Dallas now with @realDonaldTrump...Reports of discord are pure fiction. Great events lined up all over Texas. Rs will win in Nov! — Reince Priebus (@Reince) June 16, 2016

Trump's team has been clear -- they believe they'll have enough to win, something campaign chairman and chief strategist Paul Manafort told reporters after he emerged earlier this month from a major donor confab in New York. Trump himself has noted his ability to wrangle earned media (i.e. free time on cable television) puts him in a position where raising the amount of money party official suspects he really needs -- north of $1 billion -- is unnecessary. But nary a donor or party official can remember of a nominee starting at such a significant disadvantage.

Trump entered May with $2.4 million in the bank and, save for the $14 million he'd raised through largely unsolicited donations throughout the course of his primary campaign, had done little to set up an aggressive small-dollar or large donor operation. Instead, he'd floated his primary efforts through $44 million of loans from his own bank account.

To put that into perspective, Mitt Romney, the party's 2012 nominee, had already raised nearly $100 million by the end of April of that election year -- and he hadn't even kicked his fundraising into high gear. Numbers aside, Romney's team had spent the primary (and even the months and years prior to it in many cases) developing and implementing their small and large dollar operations. Fundraising chairs, bundlers and at-the-ready event hosts were identified in all 50 states -- and none of that included the campaign's own joint-fundraising operation with RNC, which pulled in more than $140 million in its first quarter of existence.

Or, another way to look at it: Sen. Rob Portman, an Ohio Republican facing a tough re-election in November, had more than $13 million in the bank at the end of the first quarter of this year. Senate candidates -- even those as proficient in fundraising as Portman -- shouldn't be more flush with cash than their party's presumptive presidential nominee.

Self-funding pitch

While Trump's "self-funding" pitch was clearly effective in the primary (throughout the months-long campaign, person after person at Trump rallies would rattle off Trump's contention that he wasn't beholden to special interests as one of his most appealing aspects), it has left him far behind Hillary Clinton and her allies. Clinton, through April, had pulled in $187.5 million and had more than $30 million in the bank. That money is already being put to work in the form of a multi-million dollar ad blitz in battleground states -- an effort, advisers say, to define Trump to the general electorate before Trump has an opportunity to defend himself -- a strategy that mimics what President Barack Obama's campaign successfully deployed against Romney in the early summer months of 2012.

Even Trump's first major foray into fundraising — ten events in nine days where he raised more than $8 million, according to one source— has been questioned as not good enough. Major donors who live in the cities where Trump is scheduled to stop say they have not even been contacted about the events. Invitations have been distributed with few local names listed as hosts. And Republican fundraisers have expressed alarm that his pace is not nearly grueling enough to close the massive financial deficit he will face, which is likely to exceed $500 million.

"At this stage, I think you got to be doing like ten events in two days," said Spencer Zwick, one of the Republican Party's most celebrated fundraisers, when told of Trump's schedule. "You've got to go around and scoop the money up."

$500 million

Trump fundraisers have internally aimed to raise about $500 million, which would be about half as much as Zwick raised for the Romney campaign just four years ago. But even bundlers outside the Trump network agree that Trump could well survive in that financial position given his command of earned media that ensures he'll be on television even without Clinton's meaty advertising buys. And given the quick clip that Trump's joint fundraising committee can raise cash — at about $450,000 per individual, thanks to fundraising laws not in place four years ago — Trump could barrel toward his goal should he recruit a few hundred donors who give the maximum.

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Yet even that $500 million number is questioned as overly rosy should Trump not execute the basic blocking and tackling of campaign fundraising. His low-dollar operation is not set to launch until the convention. Some Republicans who have raised money for every previous presidential campaign say they have not received a single contact from Trump's team. And even those who are paraded by the RNC as top financiers tell CNN that they haven't made a single call to their networks for the Trump Victory Fund.

Charles Urstadt, who was named to the RNC's Presidential Trust committee, said he wasn't expecting to get his marching orders until the Republican National Convention next month.

"I've made contributions but no calls," Urstadt said, a sentiment echoed by at least one other Presidential Trust member. "I can't relay the efforts made because, frankly, I haven't participated."

It's not just Trump's fundraisers declining to make calls — it's Trump himself. Republicans have expressed frustration both with how Trump wants to spend the cash in his bank account, but also his reluctance to do the wooing that is part and parcel of modern donor maintenance.

Intimate receptions

While Trump is described by those who have seen him as charming in these intimate receptions -- he gamely signed a newspaper column in Sharpie that a donor in Houston wrote to endorse him -- Republican fundraisers recognize that whether it's disinterest, a poor work ethic or some combination of both, he's undermining himself.

"There are very few people who like to do the ask, so I can understand why Donald Trump — first time at age 70 — doesn't want to make the ask," said one longtime RNC fundraiser. "He doesn't want to make the calls. He's just in a little bit better position to avoid it than I am."

Trump himself appears to acknowledge his general distaste for the practice, telling NBC News in an interview last week: "I don't ask for money. They come to me."

Trump's presence at the top of the ticket presents a challenge and an opportunity for Republicans. On the plus side, many Republicans are arguing to donors that it's time to give money down-ticket to help save the House and Senate majorities -- an argument that becomes much easier with Trump's poll numbers flagging. Big-spending outside groups, like the McConnell-aligned super PAC Senate Leadership Fund, are seeing big donors move their way, having pulled in $39 million through March.

And the Koch brothers' Americans for Prosperity is expected to spend heavily in key Senate races this cycle -- as it avoids helping Donald Trump.

Yet what concerns Republicans on Capitol Hill are Trump's controversial comments, which could hurt their party down-ticket and imperil vulnerable GOP senators. If their poll numbers suffer, their money could dry up, as well, some fear.

For that reason, many Republicans have begun to make the case directly to Trump that he needs to pull together his campaign and avoid making controversial remarks that overshadow the GOP election-year message. Most recently, GOP leaders scoffed at Trump's decision to renew his demand to temporarily ban Muslims entering the United States -- a topic many believe hurts the GOP brand and its ability to broaden the party's appeal.

"No," Sen. Roger Wicker, chairman of the National Republican Senatorial Committee, told CNN when asked if Trump's comments were helpful to his Senate candidates. Many are already keeping their distance -- either by avoiding outright endorsements or making concerted efforts to distance themselves or outright criticize the presumptive nominee. The possibility of the need to abandon Trump completely is a real, if early-stage conversation, inside several battleground state campaigns, according to two officials, even as the idea of ridding Trump from the ticket is largely scoffed at as a real thing.

Sen. Pat Toomey of Pennsylvania, who is running in one of the most competitive Senate races in the country, won't back Trump, who could turn off swing voters in suburban Philadelphia who Toomey is trying to court. Yet Toomey realizes he's stuck with Trump, dismissing talk that he could be removed in the convention with a candidate who has broader appeal and could raise more money.

"I understand he has the majority of the votes, so I think the outcome is ordained by that fact," Toomey told CNN.