The first vote-a-rama on a Senate budget resolution in four years offers each party a chance to force the other to cast politically treacherous votes, and both sides are lining up for the opportunity, which could begin as early as Friday.

Sen. Barbara Boxer of California, the Democrats’ chief deputy whip, said Wednesday that she believes party leaders would try to pair tough Republican amendments with Democratic alternatives. “We’ll have side-by-sides. They would be related to the topic,” she said.

Minority Whip John Cornyn of Texas said the GOP had a “collective list of priority amendments.” The options include a mandate for the budget to be balanced in a 10-year window and a proposal to strike a Democratic provision for $975 billion in tax increases on wealthy taxpayers and corporations to help reduce the deficit.

Senate Majority Leader Harry Reid, D-Nev., and the White House have worked in tandem to shield vulnerable Senate Democrats from tough votes that could provide opponents with campaign fodder. But regardless of those concerns, the Senate this week will finish its first budget debate in four years.

Senate Budget Chairwoman Patty Murray, D-Wash., kicked off formal floor proceedings 5 p.m. Wednesday. Thursday is likely to be a long day of speechmaking, with rank-and-file lawmakers of both parties eager to talk.

While each party is guaranteed 25 hours of debate on the budget resolution under the rules, the main event — a continuous sequence on nonbinding votes known as a vote-a-rama — is expected to begin Friday.

A senior Republican aide said Wednesday he didn’t expect Republicans would yield back debate time until after a full day of budget speeches Thursday, likely setting up the marathon floor session for Friday. Depending on the number of amendments offered, it could linger into Saturday. Reid has threatened to keep the Senate in session until the budget is finished, a gambit intended to spur senators to limit their amendments so they can more quickly begin a two-week recess scheduled to start next week.

Though the debate is limited to 50 hours, it does not include time for actual amendment votes, which could take 15 minutes apiece.

On Wednesday, Reid shot down a suggestion by Sen. Jeff Sessions of Alabama, the ranking member of the Budget Committee, that the Senate delay the budget resolution debate until the week of April 8. That time frame would match the target date for delivery of President Barack Obama’s own fiscal 2014 budget blueprint.

Taking up the budget resolution before the White House delivers its budget allows Democrats to sidestep one potentially embarrassing vote by not giving the GOP time to introduce a version of the administration plan for an up-or-down vote.

During debate on a different piece of legislation last year, Republicans forced a vote on Obama’s fiscal 2013 budget request, and they were able to trumpet the fact that the White House plan got no votes.

The White House has said it expects to unveil its budget the week of April 8, two months late, and has blamed the delay on the prolonged debt limit and the fiscal cliff battles. Reid has denied any concerns about the Obama budget and suggested he wants to finish the budget this week so Democrats can pivot quickly after the break to new initiatives such as gun restrictions, an immigration policy overhaul and a water resources bill.

Democrats are sure to force a vote on the House Republican budget, unless the Senate GOP offers a similar proposal. “I don’t think there’s any hesitation to vote on the House budget,” Cornyn said.

Democrats also are planning amendments to target individual pieces of House Budget Chairman Paul D. Ryan’s plan, including changes to the way Medicare is administered.

Republicans were lining up targeted amendments that would address provisions of the health care overhaul (PL 111-148, PL 111-152), restrict the Environmental Protection Agency and insist on a revenue-neutral tax overhaul.

“The number of amendments that we hear may be a few less than the norm,” said Foreign Relations ranking member Bob Corker, R-Tenn.

Sen. Mike Johanns, R-Neb., might try to restrict fly-overs by EPA aircraft above private property, while Boxer envisions a counterproposal to allow them when needed “to protect the health and safety of the people,” for example, when surveying a toxic spill.

Other potential Republican amendments include a plan from Utah Sen. Orrin G. Hatch to repeal the 2.3 percent medical device tax in the health care overhaul, a proposal from Ohio Sen. Rob Portman to require creation of a reserve fund to support a revenue-neutral tax overhaul and a number of curbs on environmental, health care and financial regulations.

Sen. Tom Coburn, R-Okla., who has traditionally taken full advantage of the vote-a- rama, told CQ Roll Call on Wednesday that he wasn’t prepared to unveil his plans quite yet. That may be in part because one tool available during the vote-a-rama is the element of surprise: A senator may offer an amendment without giving colleagues notice.