For US President Barack Obama and congressional Democrats, this month's budget battles brought about a remarkable period of party unity, a welcome change for the White House after a summer of disputes over possible military action in Syria, government spying programs and the president's pick to lead the Federal Reserve.

But Democratic solidarity will face a tougher test during the broader budget talks following the reopening of the government and the increase of Treasury's borrowing authority. While the prospect of a large-scale agreement is slim, Republicans will try to extract concessions from Obama on spending, deficit reduction and entitlement reform — all areas where Democratic lawmakers have worried the president is willing to give up too much.

"When things get serious, some of these negotiations are going to be awfully tough for people," Jim Manley, former adviser to Senate Majority Leader Harry Reid, D-Nev., said of congressional Democrats.

Throughout the 16-day shutdown and march toward the debt ceiling deadline, congressional Democrats lined up solidly behind Obama and his vow to not negotiate with Republicans. It was a hard-line stance that many in the party wished he had taken during previous fiscal fights.

Democratic unity was further bolstered by the fissures that emerged among Republicans and a burst of polling that showed the GOP was taking the brunt of the public's blame for the shutdown. And in the end, every congressional Democrat voted for the deal that keeps the government open until Jan. 15, lifts the debt ceiling until Feb. 7, and opens two months of budget negotiations.

But if any agreement does emerge from those talks, it will likely require Obama to make concessions that could rankle his Democratic allies.

The biggest sticking point could be over reforms to federal benefit programs, which Democrats have refused to accept without accompanying increases in tax revenue — a non-starter for GOP leaders. The budget plan Obama outlined this year put Democrats on edge because it proposed bold changes to Medicare and Social Security.

One possible compromise in the end-of-the-year talks may involve Obama offering more modest entitlement changes in exchange for easing the automatic spending cuts known as the sequester, echoing an idea floated by House Republicans during the shutdown.

The sequester is unpopular with both parties. But there is little consensus over how to offset the spending cuts, which are scheduled to intensify in mid-January, with the Pentagon bearing most of the cuts.

Democrats don't appear to want to compromise over spending levels. Party leaders say they already gave in to Republicans by agreeing to let the GOP extend the current sequester levels through Jan. 15 as part of the short-term deal to end the shutdown.

White House officials say Obama has made clear to Democrats that no one will emerge from budget negotiations with everything on his wish list.

"He will not get in a budget negotiation everything he wants, and neither will Democrats and neither will Republicans," White House spokesman Jay Carney said.

Patrick Griffin, who served as legislative director for President Bill Clinton, said Obama's challenge will be balancing an outcome that could help build bipartisan support for his other agenda items with the desires of Democrats facing re-election in 2014.

"What might be good for the president for his next three years might not be the same agenda that's good for (Senate Majority Leader) Harry Reid and the caucus for the next year," he said.

Before the shutdown and debt debate, it appeared as though the ties between the White House and Democrats were fraying. Liberal Democrats were angry over revelations that the White House was continuing government spying programs started under President George W. Bush. Many in the party opposed Obama's call for possible military action in Syria following a chemical weapons attack. And several Democratic lawmakers revolted against Obama's preferred choice to lead the Federal Reserve, forcing economist Lawrence Summers to withdraw his name from consideration even before he could be nominated.

Fearing the fractures could bleed over into the budget battles, the White House, along with Reid and House Minority Leader Nancy Pelosi, spent weeks trying to shore up support within the party. Obama was in frequent contact with party leaders and held meetings with the full Democratic caucus, both on Capitol Hill and at the White House.

Democratic officials say the unity spilled over into fundraising efforts. The DNC, which has struggled to raise money this year, said it brought in $850,000 the day before the government shutdown, marking its best one-day fundraising haul since before the November election. And halfway through the month, DNC communications director Mo Elleithee said October is already the committee's biggest fundraising month of the year. He did not say how much the DNC has raised so far this month.

Sean Spicer, communications director for the Republican National Committee, said the GOP has also seen a "large uptick" in fundraising since the end of September, but he did not provide specific numbers.