Sen. Jeanne Shaheen (D-N.H.) and Sen. Pat Toomey (R-Pa.) talk about their crop insurance amendment to the farm bill on June 14. The bill has led to rare displays of bipartisanship. (J. Scott Applewhite/AP)

To the purported short­list of certainties in life — death and taxes — add large, bipartisan support in the Senate for the farm bill.

Despite the pattern in recent years of intense partisan acrimony, backroom bickering and publicly staged fights over nearly every piece of legislation, the Senate has begun to plod through a nearly $1 trillion farm bill that is likely to get a bipartisan vote for its approval by week’s end.

If the coalition of Northern and Western senators holds together through dozens of amendments this week, it will yield the second large vote for a substantial piece of legislation in the polarized Senate in the past three months. In March, 74 senators, a majority of both Democrats and Republicans, supported a bill to continue the program that funds the federal highway and bridge construction program.

This flurry of activity has produced hope in some corners that the “world’s greatest deliberative body” is emerging from a period of prolonged paralysis to begin approving legislation. These optimists see this as the first step toward building a functional coalition across party lines to tackle the big fiscal issues that loom over the government as the end of the year approaches. The country faces a serious fiscal crisis unless a deal is struck by Jan. 1 to stave off massive tax increases and spending cuts— which were written into law last summer to avert a crisis then.

“It’s a different Senate than it was three months ago. People are working together,” said Sen. Charles E. Schumer (D-N.Y.).

On Monday night, a senior Republican, Sen. Saxby Chambliss (Ga.), even stopped by a fundraising event for a Democrat, Sen. Mark R. Warner (Va.), to show his support, an extremely rare display of bipartisanship during which the two promoted their work together on a substantial debt-reduction package. Warner and Chambliss convened another bipartisan huddle Tuesday with Erskine Bowles, the Democratic co-chairman of the Simpson-Bowles debt commission, in preparation for the post-election session, in which Congress is expected to tackle the fiscal issues.

Republicans, who are in the minority in the Senate, said the chamber can still function if the Democrats in charge allow it to happen. The farm bill is the latest in a string of measures that went through what insiders call “regular order” — a committee drafted a bill over several months, sent it to the larger Senate and, after haggling, Majority Leader Harry M. Reid (D-Nev.) agreed to allow a few dozen amendments.

That process led to success on the highway bill, as well as changes to the Postal Service and the Food and Drug Administration, and it probably will work on the farm bill, too. On these important issues, Republicans have supported the final legislation because they have been allowed to offer amendments. When Reid blocks their ability to amend bills, more often than not Republicans stand as one and filibuster legislation, even if they support its premise.

Cynics see the recent successful votes as a sign that the Senate is returning to its roots as a body in which lawmakers promote their local self-interests, first and foremost, with pork-barrel projects.

“It says a lot about farm politics,” said Sen. Lindsey O. Graham (R-S.C.), part of a Southern bloc that does not like the farm bill’s treatment of its region’s crops. “The only thing I can tell you that will get a bipartisan crowd here is if you screw with the Guard and reserves or you start messing with the farmers.”

Reminded of the highway vote, Graham laughed. “Yeah, roads, too. Anything that deals with your back yard.”

After all, in 2008, bipartisan support for the farm bill was so strong that it overcame a veto from the Bush White House, with 82 senators voting for the final draft.

What happens in the GOP-controlled House is a different story.

The highway bill remains logjammed between the Senate’s legislation and the House’s inability to approve its own plan as a June 30 deadline looms. This is creating a miniature version of the brinkmanship that marked most of the debt and deficit fights on Capitol Hill last year.

Even Chambliss, who has spent most of the past two years working with Warner on finding common ground, saw little from the farm bill to generate hope for a large deal on tax and debt issues. “I hope it breeds something, but I don’t think you can [expect] anything in that regard,” he said Tuesday.

The fiscal quagmire that Congress will face in the lame-duck session is so monumental that it will take more than the usual measures to get the job done, according to longtime lawmakers and staffers. It will require a prolonged negotiation by the House and Senate leadership, with a follow-up effort by the committees. Still, the optimists think that the small steps taken this spring could help pave the way for cooperation later.

“Let us pray,” Schumer said, adding that he is willing to use “whichever religion that will get the message upstairs.”