They're taking baby steps, often coming around begrudgingly and certainly not in any unified front.

But longtime mainstream Republicans are slowly warming to accepting Donald Trump as their presidential nominee – the latest indication of the New York City real estate mogul's prevailing position in the GOP primary race.

No, Trump has not earned the flood of establishment-aligned endorsements a typical front-runner in his position would have garnered by now, and skeptics and holdouts remain. He still only boasts the endorsement of a single U.S senator and a trio of governors, the smallest list of the three remaining Republicans in the 2016 contest.

Yet over the last two weeks – which have featured his shattering 35-point victory in New York and his rout of five Northeastern states on Tuesday – Trump gradually has picked up praise, appreciation and even full-throated backing from key players in the much-maligned but still powerful establishment wing of the party.

"The movement I see is politically aware folks seeing his nomination more and more likely," says Grover Norquist, president of the conservative Washington-based group Americans For Tax Reform. "People are now looking for reasons to be accepting of his nomination."

With only 10 primary contests remaining and Texas Sen. Ted Cruz and Ohio Gov. John Kasich both mathematically unable to attain the necessary delegates to win the nomination outright, the gravitation toward Trump equates to less of a full, tight embrace than a limp arm patting him on the back.

But sentiment is still moving his way.

Following Trump's "America First" foreign policy speech this week, Tennessee Sen. Bob Corker, chairman of the Senate Foreign Relations Committee, barnstormed cable news to herald Trump for challenging the Washington establishment on global affairs.

"I thought it marked a big transition in this campaign. And I actually thought the speech was a very good speech," Corker said Thursday on MSNBC.

Back in March, Ron Kaufman, a key adviser to Mitt Romney's 2012 presidential bid and a Republican National Committeeman from Massachusetts, was championing a contested national convention to dislodge Trump.

"If that's the only way to stop Trump, it makes sense," he told The Associated Press.

Now, eight weeks later, Kaufman is comparing Trump to former President Ronald Reagan, dubbing him "an eastern populist " and all but declaring him the nominee.

Many in the Republican donor community also have quietly resigned themselves to Trump as their standard-bearer, for better or for worse, especially after his series of emphatic wins on Tuesday.

Since then, their reluctance to take part in any further anti-Trump efforts has only hardened.

"The anti-Trump stuff has failed. It's run its course. It won't be able to raise any more money," says one veteran GOP donor who fundraised for one of Trump's former rivals. "The donor community recognizes Trump's going to be the nominee. They're not getting on board with Trump, but they're not in denial."

And on Wednesday, Florida Gov. Rick Scott, who endorsed Trump last month, took to Facebook to call for an end to the "Stop Trump" movement.

"Donald Trump is going to be our nominee, and he is going to be on the ballot as the Republican candidate for president," Scott wrote. "We've had an extensive debate amongst ourselves, it is now time to get serious about winning in November. This was a hard-fought campaign, but now is the time for Republicans to unite."

Yet even with the growing gravitation toward Trump by GOP elites, it's apparent that much of his newfound favor is aided by a biting and pervasive distaste for Cruz.

Despite being the most viable alternative to Trump, Cruz still has just four Senate endorsements – including more than one that lacked full-fledged enthusiasm . South Carolina Sen. Lindsey Graham, who is now helping Cruz, previously dubbed him an "opportunist" and said the Texas senator could lead to the party's downfall.

Cruz's failure to lock down a flurry of significant endorsements – including those of his former rivals, Sens. Marco Rubio of Florida and Rand Paul of Texas – since his last primary victory in Wisconsin underscores his unpopularity within the party.

Reinforcing that problem, former House Speaker John Boehner set off a firestorm Thursday when a college newspaper published remarks of him calling Cruz "Lucifer in the flesh."

Boehner also shared that he has become golfing and texting buddies with Trump and indicated he expected to vote for the former reality television star as his party's nominee.

"There are a lot of people that think Cruz has a less chance of getting elected than Trump and there's a lot of people that don't like Cruz and think the more the public sees of him, the less they will like him," says a prominent GOP powerbroker and attorney, who asked for anonymity in exchange for candor about the candidates.

Haley Barbour, the former Mississippi governor and past chairman of the Republican National Committee, adds that there are two discernibly growing groups in GOP leadership circles: those who are open to Trump, and those who are still working through the process.

"There some people reconciling themselves that Trump will get the majority and have the intention of supporting the nominee against Hillary Clinton, and are working through, 'How do I go about doing this?' Barbour says. "There are others who say, 'He's not there yet' – which he isn't – 'I worry he can't win, I have no idea what he would do if he were president.' This group would say, 'I'm not going to get in yet.'"

Trump's team is already prepping an aggressive push to twist arms on Capitol Hill, something that conceivably will be easier if he's able to knock Cruz off in Indiana on Tuesday.

The combination of steady congressional wooing along with a stream of additional policy speeches is designed to make institutional Republicans comfortable with Trump, and to signal that he has more in common with them substantively than they might realize.

But as the Trump campaign must know, their candidate's most persuasive establishment lure is the millions of voters who have cast ballots for him.

Two days after Trump stomped through Pennsylvania with a 35-point victory, he announced the endorsement of Rep. Bill Shuster, the chairman of the House Transportation and Infrastructure Committee, one of two congressional endorsements he netted Thursday.

In a release, Shuster highlighted Trump's private sector business acumen and passion for economic development. But first, he noted that Trump accomplished something his rivals had not, which was win the congressman's home district.