Senate Democrats aren’t planning a shutdown showdown with Republicans over the sequester, as they prepare to move forward with an omnibus package keeping the government open past March 27, according to three senior Democratic aides.

After both parties’ sequester bills failed in the Senate on Thursday, lawmakers were already looking ahead to the expiring continuing resolution as the next deadline and opportunity to avert or alter the $85 billion in cuts set to go into effect Friday.

But Democratic leaders don’t seem willing to risk a government shutdown by insisting that any funding bill block all of the sequester’s cuts.

Democrats feel they could argue in a shutdown scenario that Republicans were shuttering the government to keep the sequester that their leadership has blamed on President Barack Obama.

“It’s not that we couldn’t win the argument if we had to, it’s that the willingness doesn’t seem to be there” from the White House, one senior Democratic aide said.

Unless the sequester’s effects are truly dramatic in the next three weeks — something no one is expecting — Democrats would be hard-pressed to risk a shutdown to block them, the thinking goes.

The hope among party leaders is that the heat will fall on the GOP in the coming months, as the effects of the sequester cuts become more apparent.

The White House repeatedly has declined to comment on the CR scenario, although the administration issued a veto threat Thursday on a Republican bill aimed at giving the White House more flexibility in carrying out the cuts.

Senate Majority Leader Harry Reid, D-Nev., when asked in a news conference whether he would demand revenue and a sequester fix in any funding bill keeping the government open, also demurred. Reid said it would depend on what House Republicans actually send over to the Senate.

The senior aide said Senate Democrats aren’t about to make a stand without the president. The current pickle — with cuts taking effect and no obvious way out — only underscores for some Democrats their concern that the White House gave away too much of its leverage in the fiscal-cliff deal by making most of the tax cuts permanent while only delaying the sequester for two months.

Obama ripped Senate Republicans on Thursday for blocking Senate Democrats’ sequester alternative and voting to “let the entire burden of deficit reduction fall squarely on the middle class.”

He said he would demand compromise at his meeting Friday with congressional leaders.

“We can build on the over $2.5 trillion in deficit reduction we’ve already achieved, but doing so will require Republicans to compromise. That’s how our democracy works, and that’s what the American people deserve,” Obama said.

Reid also said he would again push for compromise, even as Speaker John A. Boehner, R-Ohio, and Senate Minority Leader Mitch McConnell, R-Ky., continued to be united against new revenue.

“What I would hope is that the Republicans there — both of them — would agree with the Republicans around the country that we should have a balanced approach to get rid of this,” he said, suggesting that an omnibus would be a way out.

To be sure, some Democrats, such as Sen. Tom Harkin of Iowa, are eager for a showdown. “The American people are on our side. … Why should we cave?” he asked.

Harkin doesn’t think it makes sense for Democrats to vote for any CR that keeps the sequester intact.

Other Democrats and especially Republican hawks such as Arizona Sen. John McCain still hold out some hope for a deal in the coming weeks that would restore some of the sequester’s cuts in the CR.

McCain voted against his party’s sequester alternative, saying it cut too deeply into defense. He said the GOP should be willing to make concessions in negotiations with Obama and that he hopes the coming cuts act as a “forcing mechanism” to bring the parties together.

McCain also warned his party that if a shutdown does come, the GOP likely would take the blame. The lesson of history is that the party that doesn’t have the White House loses shutdown fights, he said.

And to any of his younger colleagues who don’t remember the last shutdown fight with President Bill Clinton in the mid-1990s, he said, “I think they should go back and look at some old clips.”

In the meantime, Appropriations Chairwoman Barbara A. Mikulski, D-Md., said she intends to move an omnibus with all 12 unfinished fiscal 2013 spending bills. That would be a far broader measure than the House’s planned package, expected to be unveiled Monday, which pairs a continuing resolution with Defense and Military Construction-VA bills.

“I will have an omnibus,” she said. “We can’t go crisis to crisis and we can’t put out bills like Noah’s ark, two by two.”

Like her House counterpart, Mikulski will write her measure in keeping with the $1.043 trillion cap set by the fiscal-cliff law. But unless Democrats succeed in persuading Republicans to include language averting the sequester, automatic cuts would then be applied to that number.

Richard C. Shelby of Alabama, ranking Republican on the Senate Appropriations Committee, threw cold water on the idea of an omnibus, however, after a meeting Thursday afternoon with Reid, McConnell and Mikulski.

“I don’t think an omnibus would go with our caucus,” Shelby said, adding that discussions were ongoing with Mikulski and House Appropriations Chairman Harold Rogers, R-Ky.

Sen. Bob Corker, R-Tenn., said appropriators should finish an omnibus assuming that the sequester stays in effect — saying that would ensure the cuts are made in a smarter way.

And Sen. John Thune, R-S.D., warned that Republicans would not accept a Democratic-written CR if it includes new tax revenue to avert the sequester.

If the omnibus efforts fail, Republicans hope to be able to persuade Democrats to cave on increased flexibility to carry out the sequester in a smarter way. Sen. James M. Inhofe, R-Okla., said he is already starting to woo more Democrats to cross over and back his flexibility measure or something similar.

Kerry Young and Niels Lesniewski contributed to this report.