Democrats studiously avoided Senate floor fights over taxes and spending before hitting the campaign trail last week, but the post-election debate on those issues promises drama and gridlock.

Democrats and Republicans agreed that a GOP buoyed by even modest Election Day additions to their ranks is unlikely to negotiate much on bills to fund the government or extend Bush-era tax cuts when Congress returns Nov. 15.

‘Much of what we will accomplish ‘ or won’t accomplish ‘ during a lame-duck [session] has to do with who is going to be elected in November,’ one senior Senate Democratic aide said. ‘Even though most of those new Senators won’t have a vote during the lame duck, if a large number of tea party Republicans are elected, sitting Republican Senators that don’t want to face a primary in 2012 will want to hew to the right, not work with Democrats to get something done.’

Eric Ueland, who served as chief of staff to former Senate Majority Leader Bill Frist (R-Tenn.), agreed. ‘When Congressional Republicans pick up seats next month, they will return to town with a greater say in how core issues are resolved, and it looks like the emphasis will be on what is feasible and achievable,’ he said.

Minority Leader Mitch McConnell (R-Ky.) could have as many as three new Members during the lame duck, if GOP candidates in Illinois, Colorado and Delaware win special elections to fill the terms of previously appointed Senators. Democrats enjoy a 59-41 advantage but have had trouble picking off even the one or two Republicans they need to beat back GOP-led filibusters. Trying to get four GOP votes could be more of a heavy lift than Senate Majority Leader Harry Reid (D-Nev.) can muster, given that Republicans are likely to be even more united after winning.

But even without the lame-duck gains, Republican leaders may want to give their Members a chance to weigh in on spending and tax policy decisions.

Senate GOP appropriators already helped to stymie spending bills earlier this year, when they banded together to demand that Democrats slash $26 billion from Obama’s budget request. Senate Democrats on the Appropriations panel adopted a proposal to cut $14 billion, but the difference was enough to create an impasse.

Just before leaving town, Democrats beat back two GOP attempts to amend the continuing resolution with a 5 percent spending cut and a proposal to kick the spending decisions to the 112th Congress, when Republicans will presumably have more votes to force larger cuts. The CR will keep government agencies funded until Dec. 3, when a new CR or omnibus will be needed to avoid a government shutdown.

History shows that political parties sometimes find value in postponing decisions on spending until the next Congress. In the 2006 lame-duck session, appropriations decisions were punted to 2007, when the new Democratic majority could more easily determine spending levels.

On Bush tax cuts, sources speculated that the impetus could be to delay action until next year or later, by passing an extension of all the 2001 and 2003 tax breaks for a year or two.

The likelihood of the Senate mustering the votes to extend only those tax cuts for couples making $250,000 and less ($200,000 for individuals) is slim, just as it was last month.

But some Democrats said they still think they have a hand to play, even if they lose seats on Election Day.

Another senior Senate Democratic aide said the majority could decide to bring up Obama’s plan to extend only middle-class tax breaks. If Republicans block that and the GOP plan to extend all the tax cuts also fails ‘ because of opposition from liberal Democrats ‘ Republicans could be in a tough position if the public blames them for letting all the tax cuts expire, the aide said.

‘If we fail to pass something on Bush tax cuts in the lame duck, they have more to lose from that than us,’ the aide said, noting Democrats would recycle their argument that Republicans are holding up middle-class tax cuts in order to give breaks to the rich.

Knowing that deals on those issues and others may be hard to reach until after Nov. 2, Reid set up procedural votes on three lower-priority bills for Nov. 17, two days after the chamber is expected to reconvene. The three votes will be on a bill to establish new food safety rules, a measure to boost enforcement of equal-pay laws, and legislation to create incentives for natural gas and electric vehicles.

Those votes are intended to give the Senate time to process the results of the elections and devise a game plan for what bipartisan agreements are possible, sources said.

Besides Bush-era tax cuts and keeping the government funded, the Senate may also have to deal in the lame duck with other tax extenders, an extension of unemployment insurance, a nuclear arms agreement with Russia, the recommendations of Obama’s debt commission and a Defense Department authorization bill, among other things.

‘While I do not expect much to change when it comes to the Republican record of ‘no,’ we remain committed to addressing the many issues facing the country,’ Reid spokeswoman Regan Lachapelle said.