Pueblo, Colorado (CNN) Donald Trump -- struggling to move past a week of one controversy after another -- is making clear that he's willing to go it alone in the final weeks of the campaign.

As the Republican nominee tries to recover from one of his toughest stretches, few prominent GOP leaders -- other than those who advise him or are on his payroll -- seem willing to launch a full-throated rescue effort.

So Trump sought to do the heavy lifting himself Monday, delivering a feisty speech here that attempted to reframe the campaign and extract him from the quagmire of the past week, which included a disappointing debate performance, a roiling controversy over whether he paid taxes, and ill-advised attacks on a Latina beauty queen -- a feud he couldn't seem to let go.

With a new CNN/ORC poll showing Democratic nominee Hillary Clinton with a five-point lead over Trump after the debate, Trump for the first time seemed to relish the role of underdog in the presidential race. He mounted an unapologetic defense of his business record, previewing lines he might deploy during his rematch with Clinton on Sunday.

Responding to a stunning New York Times report over the weekend that he may have paid no taxes for the last 18 years, Trump acknowledged here that he had been a "big beneficiary" of "the unfairness of the tax laws." He acknowledged that he "brilliantly" used U.S. tax laws to pay as little in federal income taxes as possible.

'I'm working for you now'

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Indeed, the day was all about Trump as few prominent Republicans rushed to his defense. House Speaker Paul Ryan, a policy wonk who once chaired the tax-writing House Ways and Means Committee, was the most senior lawmaker to address Trump's troubles Monday in comments that were relatively tepid.

"I don't think it's that harmful," he told local reporters in Michigan, according to the Detroit Free Press . "I think people who don't like him are going to continue disliking him."

Back in Colorado, Trump took on the stance of a fighter as he detailed his financial troubles in the 1990s -- which he described as a "bad time" and an "ugly time" -- boasting that he never considered giving up, and compared his own losses to those of working class voters across America.

"When the odds are stacked against me and you -- because many of you people are the same way -- when people say it can't be done, that's when we just get started," Trump said. "We are looking for a comeback."

"The thing that motivates me the most is when people tell me something is absolutely impossible," Trump said. "For me, impossible is just a starting point."

Across the country at Clinton's event in Ohio -- a state that may be beyond her reach despite its bellwether status in past elections -- the former secretary of state sharply pointed out that it was difficult for Trump to claim stellar business skills after declaring $916 million in losses in his 1995 tax records, according to the weekend report in the New York Times.

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"Here is my question: What kind of genius loses a billion dollars in a single year?" Clinton asked.

Verge of unraveling

Before attempting to reframe his life story as one of resilience and overcoming obstacles, Trump's campaign seemed at the verge of unraveling this week, once again sending GOP lawmakers slinking away from their flailing nominee, as they try to contain the collateral damage to vulnerable House and Senate candidates.

Somewhat laughably, Trump blamed the fact that he failed to prosecute his case against Clinton in the first debate on a faulty microphone. He then attempted a Twitter takedown of former Miss Universe Alicia Machado, a Clinton supporter who he had once criticized as overweight. Before long he was mired in the controversy over The New York Times story that found his reported losses may have resulted in him not paying federal income taxes for 18 years.

CNN has not independently verified the documents' authenticity, but Trump's campaign has not challenged any of the facts reported by The Times.

Trump's apparent self-sabotage -- or perhaps merely tone-deafness -- continued Monday morning at a forum in Virginia with the Retired American Warriors PAC where he seemed to suggest that U.S. soldiers and veterans commit suicide because "they can't handle" post-traumatic stress or weren't strong enough.

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

At the same forum, he also pointedly questioned the U.S. approach to defeating ISIS, wondering aloud whether airstrikes by the U.S. and its allies are actually taking out members of ISIS.

"We don't have victory," Trump said at the veterans' forum in Virginia. "We're dropping things all over the place. Who knows what they are hitting? Who knows how many people are being killed? Who knows if they're the right people?"

As Trump's comments about PTSD blazed across social media, news reports emerged that New York's (Democratic) Attorney General issued a cease-and-desist letter to Trump's charitable foundation, ordering it to stop raising money in the state after a series of reports about the foundation's questionable spending.

Gleeful Democrats

While most Republicans were silent Monday, Democrats were gleeful -- doing their part to stir up the uproar over Trump's comments about PTSD, with even the White House weighing in.

"The commander in chief made a firm declaration that it is not a sign of weakness to get help," White House spokesman Josh Earnest said, alluding to President Barack Obama's comments during a town hall with service members last week moderated by CNN's Jake Tapper.

"In fact, it's a sign of character, and a sign of strength to ensure that you are taking care of yourself. And the president has acknowledged the cultural barriers in the military to changing attitudes about this," Earnest said.

For much of the past month, Republican leaders believed that Trump was finally on message and making an effective case against Clinton. His poll numbers rose, giving a boost to GOP senators down-ticket while improving Republican prospects of keeping the House.

But his feud with Machado, renewed questions over his taxes and his rocky performance at the first debate have once again renewed long-standing concerns within GOP ranks that their standard bearer remains an unpredictable wild card when it comes to their party down-ticket.

"Every prediction I've made has been wrong about Mr. Trump and his impact," said Sen. John Cornyn, the No. 2 Republican, who told CNN earlier this year that Trump could be an "albatross" for his party.

Asked about the next debate, Cornyn said: "We'd like to see him do better. Obviously, he doesn't have as much experience as Secretary Clinton — and it showed" at the Hofstra debate.

Asked about Trump's attacks on Machado, Sen. John Barrasso of Wyoming, the No. 4 Senate Republican, said Trump "is at his best" when he focuses on economic issues and national security -- not personal matters.

"I would focus on Hillary's record on politics of 30 years," Barrasso said when asked about Trump bringing up Bill Clinton's sex scandals. "This is a change election -- change versus more of the same and this country cannot afford to have the next four years to be like the last eight years with Obama."

Sen. Bill Cassidy of Louisiana also said Trump needs to re-engage on the issues that drove up his poll numbers in late August and early September.

"You know I can't comment on that, it's not what I would do," Cassidy said when asked about Trump relitigating the Clinton scandals from the 1990s. "I think people know that. Folks now — they're hurting and they want to know somebody understands."

Indeed, GOP leaders publicly and privately have long shown a level of discomfort with Trump's unorthodox campaign — especially in the aftermath of last week's events.

At a press conference to wrap up the pre-election congressional session, Senate Majority Leader Mitch McConnell would not talk about Trump's impact on the battle for the Senate majority.

"Look to avoid wasting our time here," McConnell told reporters, "this is not something I'm going to discuss today -- the implications of the presidential race on the Senate."

Asked why he wouldn't answer Trump questions, McConnell said flatly: "Because I choose not to.