Senate Minority Leader Charles E. Schumer, center, discusses a Democratic proposal to improve schools. From left are House Minority Leader Nancy Pelosi (D-Calif.), National Education Association President Lily Eskelsen García and American Federation of Teachers President Randi Weingarten. (Aaron P. Bernstein/Getty Images)

Democrats have spent years working to counter Republican attacks on them as big-spending liberals, from passage of the last balanced budget during the Bill Clinton years to Barack Obama’s insistence that the Affordable Care Act pay for itself.

But now that Republicans have blown up the deficit with a $1.5 trillion tax cut and other high-cost policies, many Democrats feel freed.

In recent months, Democratic lawmakers and candidates have endorsed plans allowing anyone to buy in to Medicare, to make college effectively debt-free, to replace the payday loan industry with small government banks and to provide a “job guarantee” that would spend to put people to work.

Sen. Brian Schatz (D-Hawaii) has introduced a bill that would make most college free. (Melina Mara/The Washington Post)

“Democrats have put ourselves at a longtime, strategic disadvantage,” said Sen. Brian Schatz (D-Hawaii), who has introduced a bill that would make most college free but has waved off questions about the cost. “We have to pay for progressive priorities, and they borrow money for theirs. After the tax cut, there’s almost no enthusiasm for worrying about how to pay for new proposals.”

The party’s revised thinking has been on display in primary campaigns, where even candidates tacking to the middle of their fields have run on expanding Medicare and funding infrastructure. It’s been adopted by congressional Democrats in their “Better Deal” proposals; last week, Senate Minority Leader Charles E. Schumer (D-N.Y.) and House Minority Leader Nancy Pelosi (D-Calif.) added a $100 billion education package to their growing manifesto.

But the new attitude is worrying some Democrats. It has been decades since the party ran a national campaign on some of these ideas; it had elected two presidents, Clinton and Obama, who ran against fiscal irresponsibility.

“Members of both parties have recently moved to dreaming big dreams without figuring out how to pay for it,” said Sen. Thomas R. Carper (D-Del.), who is up for reelection this year but not facing a serious Republican challenger. “I came [to Congress] with the idea that we’d be fiscally responsible, and neither party seems to be. My hope is we’ll get back to that sooner rather than later.”

Since the tax cut’s passage, the trend has been in the other direction. When Sen. Bernie Sanders of Vermont, an independent who ran for the Democratic presidential nomination in 2016, introduced his universal Medicare bill last year, he did not immediately say how it would be paid for. He had offered a list of potential tax hikes to pay for it but didn’t include them in the bill.

One paper produced by the Center on Budget and Policy Priorities has proposed a job guarantee pegged at $543 billion a year with some savings from lower welfare spending but greater spending overall.

Sen. Dianne Feinstein (D-Calif.) supports the expansion of Medicare to people 55 and older. (Jonathan Ernst/Reuters)

And in a new ad for her reelection campaign, Sen. Dianne Feinstein (D-Calif.), who is facing a challenge this year from her own party, tells California’s primary voters that she favors a health care “public option” and the expansion of Medicare to people 55 and older, with no suggestion of how it would be paid for.

Supporters of the jobs guarantee, of free college tuition and of higher teacher salaries have sold their plans the same way. In some cases, they suggest the bill could be taken care of with the elimination of part or all of last year’s tax cut. In others, they suggest that it’s time to stop fussing about the cost.

“Corporate interests have controlled the agenda in Washington for decades so we can’t tinker at the margins and expect to rebuild the middle class and stamp out inequality,” Sen. Kirsten Gillibrand (D-N.Y.) told the left-wing magazine the Nation after endorsing the jobs guarantee.

Pelosi, who has given candidates wide room to run against her, is also somewhat cautious about the spending plans. Just as Obama suggested that rolling back most of the George W. Bush-era tax cuts for wealthy Americans could fund his plans, Pelosi has preferred to tie the spending proposals to a rollback of President Trump’s tax cuts.

In an interview this month at the Peter G. Peterson Foundation’s fiscal summit, Pelosi called the tax cut package “a dark cloud over our children’s future” and a worrisome source of debt. Asked about the jobs guarantee, Pelosi said she needed to see how much it might cost.

“Democrats believe you must pay as you go,” Pelosi said.

But some Democrats pointed to Hillary Clinton’s presidential run in 2016 as a cautionary tale, seeing spelling out the cost as part of a policy rollout as a trap. While her campaign designed spending plans that could be paid for, adding nothing to the deficit, Trump proposed huge tax cuts and vast spending while also promising to wipe out the national debt within eight years.

“We fronted the idea that everything would be paid for, that everything added up, and I don’t think we got any credit for it,” said Brian Fallon, Clinton’s spokesman during the campaign. He is now a spokesman for Democratic groups working against the tax cut.

Republicans passed a $1.5 trillion tax cut last year, following it up with a $1.3 trillion spending plan this year. But while their party has long nurtured an image as fiscal watchdogs, they have barely talked about spending on the campaign trail.

Political reality, Democrats said, would mean that their big ideas came with at least some arguments for higher taxes. That pitch had not seriously been tested in a general election; since 1992, Democrats had run only on raising taxes for the wealthiest.

“If you’re telling people that you’ll increase their taxes dramatically so that, theoretically, they’ll have lower premiums — look, that’s not going to be successful politically,” said former senator Kent Conrad (D-N.D.), who used his perch as Budget Committee chairman to warn about the growing debt.

Democrats with an eye on 2018 and beyond are no longer talking, though, about a “grand bargain” that would reduce the deficit by raising taxes and slashing social insurance, an idea that was not popular in the first place. Many say it’s time for the party to promise not to undo tax cuts to shrink the deficit, but to spend on popular programs.

Rep. Ro Khanna (D-Calif.): “If you’re unemployed, you get a job. If your kid wants to go to a state college, he goes for free.” (Alyssa Schukar/For The Washington Post)

“If I were talking to the people who do our messaging — I still need to figure out who that is — I’d have a chart of all the Republican spending on defense and tax cuts and then a simple, five-point chart of what the Democrats would give you instead,” said Rep. Ro Khanna (D-Calif.), a member of the Congressional Progressive Caucus. “You get $5,000 back with the earned income tax credit. If you’re unemployed, you get a job. If your kid wants to go to a state college, he goes for free.”

Even Pelosi, who took some flak from her party’s left for the Peterson interview, has adopted the “choice” argument. If both parties are interested in bor­rowing money to pay for their vision, Democrats’ vision must be easier to sell.

“Wouldn’t it have been better if we had spent over a trillion dollars on infrastructure,” Pelosi asked, instead of “tax breaks for the wealthy?”

Erica Werner contributed to this report.