House Democratic Leader Nancy Pelosi of Calif., right, and Senate Minority Leader Harry Reid of Nev., left, walk to talk to reporters on Capitol Hill in Washington, Wednesday, Oct. 28, 2015, about the passage of a budget by the House. (AP Photo/Susan Walsh)

The budget victory party is already over for Democrats in Congress and the focus now is on preventing a government shutdown in December.

Democratic leaders are anticipating a weeks-long fight with Republicans who could attach controversial provisions, like defunding Planned Parenthood, to the spending legislation that is necessary to prevent a government shutdown later this year. Their plan is to stay unified and refuse to vote on bills that they don’t like.

“Who would have thought the government would shutdown over closing Planned Parenthood clinics,” Senate Democratic Policy Committee Chairman Charles E. Schumer said in an interview. “There’s a decent chance the government will shut down over one of these riders but [Republicans will] lose. And we’ve agreed: Nancy [Pelosi], Harry [Reid], the president, we’re locking arms on no poison pill riders.”

The two-year budget deal approved last week by Congress to increase discretionary spending by $80 billion over two years and extend the debt limit through 2017 met nearly every budget demand laid out this year by Democrats. Leaders can also tap into an additional $32 billion from an off-budget war account, the Overseas Contingency Operations fund, for a total of $112 billion in new spending.

While this deal settled the fight over how much the government should spend on domestic and military programs, there is still work to be completed on how that funding should be divvied up among agencies and federal programs.

In the coming weeks the Appropriations Committees will begin crafting an omnibus spending bill that must be signed into law by Dec. 11 to keep the government open, and Republicans have a long list of policy proposals they would like to tuck into the legislation.

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Buoyed by what they view as a victory in the budget deal negotiations, Democrats are now firing warning shots that they will stay united to prevent Republicans from attaching such riders to the omnibus that could seek to cut off funding for Planned Parenthood or dismantle some of President Obama’s top priorities, including Obamacare, new environmental rules and executive actions on immigration.

New House Speaker Paul D. Ryan (R-Wis.) is trying to temper expectations that Republicans will pick a shutdown fight over policy concerns that have little chance of getting through the Senate or past a presidential veto.

“I think we need to be very clear about what it is we can and cannot achieve, and not set expectations that we know we can’t reach, given the constraints of the Constitution.” Ryan said in a interview Sunday with CNN in response to a question about trying to cut off Planned Parenthood’s funding later this year.

But in keeping with his pledge to allow for a more wide open legislative process in the House, he added that these issues would be decided by members and not solely by leadership.

“By not controlling the process so tightly held here, the speakership, by letting it go forward, I don’t know what the outcome is going to be,” he said.

Democrats spent the days before and after the budget bill passed setting up expectations for the appropriations fight.

“House Democrats are holding hands with the president, with the Senate Democrats,” said Senate Minority Leader Harry Reid on Wednesday. “We’re not going to take these vexatious, idealistic riders.”

Reid and House Minority Leader Nancy Pelosi (D-Calif.) successfully convinced every single Democrat in Congress to line up and vote for the budget deal. It was a huge victory that leaders hope will inspire members to stay unified for the potential fight ahead.

“Our caucus considers this not only a big victory but one that we actually helped create,” Schumer said. “We said months and months ago that this was going to be our biggest problem and we had to be prepared.”

Early this year Democrats decided that the only way to fight deep spending cuts would be for Obama to threaten to veto any spending bills that didn’t maintain equal spending boosts for military and domestic programs. Democrats would then vote against all of the bills to send the message that Republicans would have to negotiate or take responsibility for a shutdown.

“We’re not going to be picked off and we’ll win the fight because they’ll look unreasonable,” Schumer said.

The plan was for members on the Appropriations Committees to work with their Republican counterparts to do the difficult work of dividing up spending so that they could have a hand in writing the bills, but then join with other Senate Democrats to block the legislation from getting a floor vote to protest the overall spending levels.

Some members worried that the strategy would require them to stand in the way of votes on critical bipartisan issues like military and veterans spending. Senate leaders had to lean on members during weekly party lunches. It worked and bills funding the military and veterans programs were blocked.

The strategy also benefited from the war raging within the House Republican conference. When a group of hard-line conservatives forced the surprise resignation of House Speaker John Boehner (R-Ohio) over, in part, their demands to defund Planned Parenthood, Democrats gained leverage. As a unified group they represent the largest block of reliable votes in the House.

Boehner was forced to cut a budget deal that could satisfy all 188 Democrats to ensure it could pass. The politics have not changed much for Ryan who will likely also have to court moderates in his party to prevent a shutdown in December.

Schumer and other Democratic leaders are hoping Republicans want to avoid taking responsibility for another shutdown and Senate Majority Leader Mitch McConnell (R-Ky.) has repeatedly vowed that none will take place.

Pelosi downplayed the risk of a shutdown last week. She said there are plenty of people in the House who will not be satisfied with any kind of deal but there are still Republicans who realize that Obama won’t sign legislation that takes apart is own agenda. She said the process might not be easy but Democrats still have the upper hand.

“There are different reasons to be optimistic,” she said. “There are many good things that are happening, will there be some things that won’t be as easy to resolve? We’ll see.”