It's well known that Speaker Dennis Hastert and Minority Leader Nancy Pelosi are barely on speaking terms in the House. Now it looks as if the Senate's leaders may be next.

Majority Leader Bill Frist is waging an aggressive campaign to cost Minority Leader Tom Daschle his job. Frist is urging Republican donors, “If you can only make one more contribution to one of our Republican Senate candidates this election cycle ... you should make that gift to John Thune!”

Thune, who narrowly lost to Senator Tim Johnson in 2002, is now challenging Daschle for his South Dakota Senate seat.

It's an uphill battle for Thune, who trails Daschle in the polls and in fund raising. But while Frist's job as majority leader is to increase his party's hold on the Senate, his decision to be so bold about politicking against Daschle is no doubt further polarizing a chamber already beset by partisan gridlock.

One of the items that's stuck in the traffic jam is the six-year transportation bill. Daschle and Senate Minority Whip Harry Reid are concerned that Republicans will once again try to shut Democrats out of conference-committee negotiations, as they did on the Medicare and energy bills last year. Daschle and Reid are therefore trying to establish a pre-conference to make sure that Democrats are included in talks about funding levels.

As Reid told The Hill last week, “I don't think there is much hope of going to conference if we don't have a pre-conference.” He added, “I don't think we're going to do a highway bill without participation from Democrats.”

Daschle and Reid have good reason to be concerned. GOP leaders met with White House Chief of Staff Andrew Card to go over details of the plan on Thursday -- without Democrats present. Frist has said he will force the conference issue sometime this week.

Of course, Republicans will say that this is one more example of Daschle's “obstructionism.” They want to force through their version of the bill without any input from Democrats. It's so pesky for them that Democrats, who represent half of all voters, want to weigh in on behalf of their constituents and actually have a debate about what the bill should include.

But if there was ever an example of how the GOP can't govern, this is it. Let's leave Democratic concerns aside for a minute. Bush wants the bill at no more than $256 billion, while the House seeks $284 billion and the Senate $319 billion. Frist and Hastert said that they don't want the president to veto the legislation -- or to risk Bush facing an embarrassing override during the election year. But no side seems willing to concede. Never mind that the bill expired September 30 and has been funded only through extensions.

The transportation bill is a key tool for lawmakers this election year; it allows members of Congress to brag at home about projects that will bring dollars and jobs to their districts. Hastert has already planned $1.5 billion worth of projects for his home state of Illinois. (And, by the way, Hastert visited Daschle's home turf on Friday to campaign for Republican Larry Diedrich, who is running against Democrat Stephanie Hersth in the June 1 special election for Representative Bill Janklow's seat.)

Republicans continue to believe that just because they have the majority in both chambers -- a bare majority, I might add -- they can do things their way. They should realize that Democrats need to peel off only a few GOP votes to achieve victory. Twenty GOP senators have said that they want at least $318 billion for the transportation bill, which could spell major headaches for Frist and Bush.

But even if there is a stalemate, look for Republicans to somehow twist the rules and find a way out of it. They could push to have projects funded through other bills, to make it look as though they're passing less expensive legislation. (They tried -- and failed -- Thursday to attach the stalled energy bill to an Internet tax ban.)

As Illinois Representative Jan Schakowsky told me earlier this week, “What you see on the floor -- it's like virtual democracy. Even if we win, we lose, because they'll hold [a vote] open for three hours,” she said, referring to the Medicare vote. “There's really an undermining of the democratic process.”

The transportation bill is the Democrats' best chance yet to teach Republicans that cutting them out of the legislative process doesn't work. Everyone knows that the Republicans need this bill. If Daschle and Reid stand firm -- as Bill Clinton did in 1995 when Newt Gingrich tried to force the president's hand on the budget -- they can show that they know how to play hardball, too. That seems to be only thing Republicans understand these days.

Mary Lynn F. Jones is online editor of The Hill. Her column on Capitol Hill politics runs each week in the online edition of The American Prospect.