Washington (CNN) -- While Vice President Joe Biden leads negotiations to avoid the next threat of a government shutdown in a Senate conference room, talks on the other side of the Capitol between House Speaker John Boehner and GOP colleagues could be tougher and decide the final deal.
Biden sat down Thursday with Republican and Democratic congressional leaders to try hammering out a deal to fund the government and cut spending. A two-week continuing resolution to fund the government that passed this week runs out March 18. The vice president said after the meeting that talks will continue.
Boehner's challenge is to maintain a hard line and insist on deeper cuts than President Barack Obama and Democrats want.
But he might also need to compromise -- and that's going to be a tough sell to Republican freshmen and other conservatives who didn't think cuts in the plan passed earlier went deep enough. They're also standing firm on policy changes in the House-passed bill, such as defunding health care and stripping all federal money from Planned Parenthood.
"I don't think compromise right now is the option, " Rep. Scott DesJarlais, a GOP freshman from Tennessee, told reporters Thursday. "What we're asking is not unreasonable. People sent us here. There was a referendum; we were sent here to cut spending."
Last month, the House of Representatives passed $61 billion in spending cuts for the rest of the fiscal year. House GOP leaders argue their bill amounts to $100 billion in cuts compared with Obama's proposed budget for 2011.
The commitment to cut $100 billion was a centerpiece of the Republican agenda that Boehner and other GOP leaders pressed as they successfully campaigned to retake control of the House in November.
One senior Republican, Rep. Mike Simpson of Idaho, who sits on the Appropriations Committee and developed the House bill, acknowledged this week the next stage in negotiations will be difficult.
"I don't know how much flexibility our conference is going to give us," he said.
Pointing to the $100 billion pledge, Simpson said, "I think Republicans are pretty stuck on those numbers.''
Boehner recognizes the political clout of the freshman class -- many of whom are in Congress because of the Tea Party's backing. And the Tea Party has made it clear that it will go after anyone -- Republican or Democrat -- who doesn't honor its demands to cut government spending.
The speaker has been holding regular talks with new members. On Thursday, Boehner took questions for about a half-hour, according to a senior GOP aide who declined to give details on the private session.
This aide said the speaker continually is talking to all House Republicans, one-on-one on the floor and in meetings, to gauge where they are on the issue. But the aide said there's nothing to negotiate until Democrats outline a specific plan of their own.
In addition to Boehner, other top House Republican leaders -- GOP Whip Kevin McCarthy, House Budget Committee Chairman Paul Ryan and Chief Deputy Whip Peter Roskam -- have been holding regular "listening sessions" with the freshmen members in small groups. These meetings cover the spending bill but also include back-and-forth about the broader policy debates coming up on next year's budget and the vote to raise the debt ceiling.
One senior leadership aide familiar with these sessions stressed they are a forum for feedback and not meant to hash over specific numbers. The aide said the meetings are also a way for freshmen to feel they are part of the process and that leaders are paying attention to their priorities.
"It's basically showing the reality of where we're at" with the deficit and the budget process, said Rep. Adam Kinzinger, an Illinois GOP freshman, who attended one of the sessions.
Kinzinger said he's waiting to see how discussions with Democrats go before committing to a bottom line on spending cuts but said he was optimistic about getting a deal through the House. Pointing to support from more than 100 Democrats on the current two-week government funding bill, Kinzinger said he's seen "a lot of willingness from Democrats to potentially work with us."
But pressure on Boehner is not just coming from GOP freshmen. Other rank-and-file conservatives are also taking a tough line on spending cuts. Many pushed unsuccessfully for another $22 billion in cuts during the House debate last month. Rep. John Campbell, R-California, voted against the House bill because he didn't think it cut enough but said he also realized the Senate was never going to accept the House bill.
"I just thought we should have started at a higher number, " Campbell said.
Because he and fellow fiscal conservatives were unable to cut spending further, Campbell said, "I think it makes it more difficult to come down much."
Another conservative, Rep. Marsha Blackburn, R-Tennessee, said she wants "the full total of what was passed by House" in a long-term bill to fund the government.
Pressed whether she could vote for less, Blackburn sidestepped the question, saying she'd have to see what was on the table. But she said she planned to keep pushing for more cuts.
"As we look at debt ceiling, as we look at (the) budget, I am again going to propose across-the-board reduction amendments," Blackburn said.
Complicating Boehner's challenge is pressure from Republicans who are insisting the policy changes attached to the House bill -- such as environmental regulations and health care restrictions -- stay in a final deal.
Rep. Chris Smith, R-New Jersey, said these so-called "policy riders" are of "paramount importance." He argued provisions to ban federal money for Planned Parenthood would "have the profound potential to save large numbers of children and mothers."
Smith said social conservatives wanted GOP leaders to include anti-abortion language in the bill that funds the government through March 18 but decided to back off. But on a longer-term spending measure, Smith said he is confident that Boehner and other GOP leaders would fight to keep the anti-abortion provisions in, saying that barring federal funding for abortions was "on par with -- at least -- this huge deficit crisis that we're facing."
Asked whether he was willing to shut down the government if the Senate doesn't go along with these policy changes, Smith said, "We'll cross that bridge when we get to it."
Other Republicans said reaching a deal on the overall level of spending cuts is more important than passing policy provisions on a funding bill.
"There are other ways and other times that we can address that if we can get to the right number," Simpson said.
Reflecting on the negotiations over spending cuts, Simpson told reporters, "We're kind of in unchartered territory. We don't know, but we're going to keep pushing to reduce spending."
CNN producer Xuan Thai contributed to this report.