It’s too soon to label the first test vote in the great trade debate of 2015 as a harbinger of total collapse ahead. But the prognosticators, the party whips and the president already have some tally sheets providing strong evidence of a cliffhanger in the making.

Congress last approved similar legislation 13 years ago, which of course is a lifetime in rhythms of the place. Still, two messages may fairly be inferred from the positions taken back then by the lawmakers who remain in office today.

Tuesday’s momentum-sapping roll call notwithstanding, at least three-fifths of senators are eager to vote to give President Barack Obama enhanced leverage to complete the expansive trade accord with 11 other nations on the Pacific Rim. Neither the hollowing out of the political center in the past decade, nor the fact that most senators were Democrats in the 107th Congress but most are Republicans now, has fundamentally changed the Senate’s personality as an ally of globalization.

The same cannot be said about those on the other side of the Capitol. Skepticism about trade liberalization has been stronger there for several decades — so much so that in 2002, President George W. Bush was granted fast track negotiating authority by the Republican House with just two votes to spare. The hurdle is looking a whole lot higher now for several reasons, starting with the intensified ideological polarization of the two party caucuses.

Seven of every 8 Republicans, and 1 in 8 Democrats, formed the razor-thin majority for final House approval of the bill giving Bush trade promotion authority. This year, only 31 of those GOP “yes” voters are still in the House, and that bloc of veteran free-traders accounts for a paltry 13 percent of the Republican Conference.

In the intervening six elections, dozens of GOP members with a pro-business mindset have been replaced by fellow Republicans less interested in helping corporate America prosper around the world than in promoting their tea party ideals and stopping Obama at every opportunity.

On the Democratic side, only two of the 25 who supported the Bush fast-track bill are still in office: Susan A. Davis of San Diego and Adam Smith of suburban Seattle, two major exporting and shipping hubs. By contrast, 61 who voted “no” are still House members and account for almost one-third of the Democratic Caucus membership.

The numbers echo the main narrative about the caucus’s evolution during the past decade. Most of the moderates who garnered support from the business community have gone, many shown the door by GOP conservatives in swing districts, and the backbone of the House Democrats is increasingly constructed of long-timer liberals who view trade deals as inevitably bad for the American workforce and the global environment.

The bottom line is that, while Obama may be doing more lobbying on trade than lawmakers have seen since the health care overhaul, his targets of opportunity in both halves of the House are smaller than they were for his predecessor. Given the Republican complaint he’s already claimed too much power that belongs on the Hill, Obama won’t have much success at beseeching Republicans for even more executive leverage. Given how few Democrats are in re-election trouble next year, and how few of them will ever consider siding with the companies in their districts over the laborers, Obama can’t expect much good to come from his West Wing meetings, rides on Air Force One or promises of 2016 fundraising help.

The back of the envelope count in the House at the moment has 60 solid GOP votes in opposition and fewer than 20 Democratic votes in favor, which means Obama is between a dozen and 20 votes short of what he needs.

The dynamic is fundamentally different in the Senate — and that, too, is reflected in the votes cast in 2002, when Congress gave up its prerogative to amend trade pacts so Bush could finalize a collection of bilateral agreements.

Almost half of today’s Senate was in Congress at the time (27 were already senators, 21 were in the House) and those veteran lawmakers broke 29-19 for fast track. While the Republicans in the group were in favor by a lopsided ratio of 6 to 1 (23-4), the Democrats were opposed by about 2 to 1 (15 “no” and 6 “yes.”)

Those half-dozen Democrats are at the core of Obama’s still-solid prospects for eventually advancing his trade agenda through the Senate.

As Tuesday’s vote showed, there is still a good amount of power gamesmanship and policy skirmishing to get through, centered on two Democratic desires. They want the fast-track bill to either include (or be accompanied by) an expansion of retraining programs for workers who lose their jobs because of globalization, and they want to pass legislation to confront China on its alleged currency manipulation. (Each of those proposals turns off some Republicans. Small-government conservatives view trade adjustment assistance as wasteful. Free-traders worry the currency measure would undermine the Pacific Rim negotiations.)

Because Democrats haven’t been given assurances they will get what they want out of the debate, almost all of them voted against formally beginning the amendment process. Proceeding to a bill requires 60 votes, and the GOP could provide only 51 of their own plus a single Democrat, Delaware’s Thomas R. Carper.

But assuming some sort of deal is eventually worked out, Obama will be able to count on four Democrats who voted “yes” in 2002 and in this year’s Finance Committee markup: ranking member Ron Wyden of Oregon, Maria Cantwell of Washington, Bill Nelson of Florida and Carper.

The president also was backed in committee by Democrats Benjamin L. Cardin of Maryland, who opposed the Bush trade deal as a House member; Michael Bennet of Colorado, the only senator in the caucus currently viewed as in viable 2016 re-election trouble; and Mark Warner of Virginia. Obama also is counting on the two other Democrats who voted for fast track 13 years ago, Dianne Feinstein of California and Patty Murray of Washington, as well as Cantwell and Claire McCaskill of Missouri.

Support from all 11 of those Democrats would push the majority into “comfortable” territory, since at least 47 Republicans are also ready to vote “yes.” But only then will the height of the cliff Obama faces in the House come into focus.

Related:

Democrats Filibuster Obama’s Fast-Track Trade Bill

White House Brushes Off Fast-Track Failure as ‘SNAFU’

5 Things That Could Get Done in a Divided Government

Signs of Life, but Don’t Expect Bipartisan Bloom

Senate Democrats Put Conditions on Fast-Track Vote

Harry Reid is a ‘Hell No’ on Fast-Track

A Ron Wyden Primary? Not Likely

The 114th: CQ Roll Call’s Guide to the New Congress

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