Leading fiscal conservatives are showering President Trump's first federal budget proposal with some of their highest praise: comparisons to Ronald Reagan.

"This is the most fiscally conservative budget since Reagan," Chris Edwards, director of tax policy studies at the Cato Institute and editor of Downsizing Government, told the Washington Examiner.

Grover Norquist, president of Americans for Tax Reform, called it a "very strong budget" and said it's what the 40th president himself would have submitted if he had both a Republican House and Senate. Democrats controlled the House for all eight years of the Reagan administration, one of the reasons conservatives cite for why even Reagan was unable to achieve enduring federal spending cuts.

Norquist then went a step further. "This is a Reaganite, limited-government, anti-waste and anti-duplication budget," he said. "It certainly makes those Republican critics who said that Trump would be a big-spending populist look like idiots."

Trump didn't run as a government-cutter during the campaign. He explicitly promised to leave Social Security and Medicare spending alone, which his first budget largely does. He campaigned on a populist platform emphasizing both economic and cultural solidarity with mostly white working-class voters.

Some Republicans argued that Trump was essentially a liberal, pointing to his past advocacy of a wealth tax and single-payer healthcare. Sen. Ted Cruz, R-Texas, a staunch fiscal conservative, was his strongest opponent in the GOP primaries.

Once Trump was elected, many on the Right expected a more protectionist version of the compassionate conservatism of the most recent Republican president, George W. Bush. The Bush administration, the Weekly Standard's Fred Barnes wrote, believed in "using what would normally be seen as liberal means — activist government —for conservative ends. And they're willing to spend more and increase the size of government in the process."

That's why some fiscal conservatives have been pleasantly surprised by the very un-Bush like discretionary domestic spending cuts in the president's budget, while liberals portray it as a typically draconian Republican attack on the social safety net and a betrayal of Trump's working-class supporters.

"When you've got $20 trillion in debt, it's nice to see a White House that's actually interested in the issue," said Andy Roth, vice president of government affairs at the Club for Growth, a fiscally conservative group that was critical of Trump during the primaries. "We welcome the spending cuts."

"A lot of the cuts are thoughtful cuts, not just blunt cuts," Edwards said. "People are getting trapped on disability where frankly they should be in the workforce."

Consequently, the Trump budget has received strong if qualified praise from leading Tea Party groups.

"Budgets are visionary documents, and President Trump's proposal would put taxpayers first by starting to direct their dollars more efficiently to the most effective programs," Heritage Action CEO Mike Needham said in a statement. "It is the type of document the president promised on the campaign trail, including some serious, structural reforms to our nation's entitlement system."

"Unfortunately, the failure to address Social Security and Medicare will make it difficult to truly rein in our nation's ever growing debt," Needham added. "Nonetheless, Trump's budget presents an opportunity to unite Republicans around fiscally responsible reforms to food stamps, disability insurance and the Earned Income Tax Credit (EITC). Even with unified Republican control of government, delivering policy victories has proven difficult in Washington, but enacting these reforms would demonstrate a true commitment to putting taxpayers first."

Budget Director Mick Mulvaney, a former South Carolina Republican congressman who was a member of the House Freedom Caucus, is hailed by fiscal conservatives as a hero in this process, especially given Trump's lack of a track record as a small-government advocate.

"I've told the story several times of sitting in the president's office with a list of possible reforms to mandatory — what some people call entitlement spending — and have the president at the end of the list go: Yes, yes, no, no, no, no," Mulvaney told reporters during Tuesday's budget briefing. "And the ‘no, no, no's' were always Social Security retirement and Medicare. Didn't change those at all because he promised people that he wouldn't."

"We have great respect for [Office of Management and Budget] Director Mulvaney," said Roth.

"He's got a very good team," Edwards added. "They're taking the job seriously. I give Trump credit for giving [Mulvaney] a lot of running room."

The conservative applause wasn't unanimous. Many considered the 3 percent growth projections required to bring the budget into balance unrealistic. Rep. Mark Sanford, R-S.C., called it a "Goldilocks scenario." Budget hawks thought it boosted Pentagon spending too much, defense hawks too little.

"[W]hile on its face, the president's budget request is balanced, the budget only accomplishes this through a combination of very strong economic forecasting and unrealistic future cuts in domestic discretionary spending," Sanford, a Freedom Caucus member, said in a statement. "Meanwhile, the proposal doesn't touch 40 percent of the annual budget — Social Security or Medicare, even though both are on a path toward insolvency."

New York Times conservative columnist Ross Douthat dismissed the Trump budget as "just Reagan-era leftovers minus the actually-serious portion of Ryanism (Medicare reform)," the latter a reference to House Speaker Paul Ryan, R-Wis.

"Ivanka's paid leave program is dumb, not a federal responsibility," said Edwards.

Yet even many of the Republicans in Congress who have declared the budget dead on arrival oppose it for cutting too much. "If Republicans actually do what they said they would do, the prospects [for cuts] would be high," said Roth, whose organization supports conservative GOP primary challengers. "But a lot of Republicans campaign one way and then don't follow through. It is my hope that if they don't follow, there will be consequences."

"We just want to see spending cuts," he continued. "That's a foreign subject to a lot of politicians here on Capitol Hill."

Federal spending is a congressional responsibility under the Constitution and presidential budget requests are frequently modified or set aside. Some of former President Barack Obama's budget proposals failed to receive a single vote in either chamber of Congress.

Some conservatives nevertheless find themselves rooting for the unconventional Trump against more traditional Hill Republicans.

"He's governing as Reagan would have, completely in the mainstream of the modern Republican Party," said Norquist. "What's interesting will be to watch those Republicans who wanted to criticize Trump when he was running to see if they are as Reaganite as Trump is."