Whoever would have guessed that trade policy could turn into the US Senate’s latest stumbling block?

Yesterday, Senate Democrats voted to block the start of debate on a bipartisan bill that would renew and broaden the President’s negotiating authority over international trade agreements. The bipartisan Trade Promotion Authority renewal legislation was introduced back in mid-April by U.S. Sen. Orrin Hatch (R-UT), U.S. Sen. Ron Wyden (D-OR), and U.S. Rep. Paul Ryan (R-WI). If passed, it would give the President authority to negotiate trade deals that would then be sent off to Congress for either rejection or approval. Because the TPA legislation would not permit Congressional amendments to the deals, the update is seen as a “fast track” option.

If passed, the TPA could be used to fast-track approval (or rejection) of the Trans-Pacific Partnership; the Partnership would include 11 other nations (both developed and developing), and stands to affect up to 40% of all US imports and exports if approved.

The block isn’t the end of the TPA renewal, but it represents a divide in the caucus, and the willingness of Democrat leadership to go against the agenda promoted by the White House.

A Senate 60-vote supermajority was required to begin debate on renewing trade promotion authority, but even pro-trade Democrats held back their support in an effort intended to boost their leverage to secure commitments on legislation that would enhance worker protections and crack down on currency manipulation.

The vote to begin debate failed, 52-45. Sen. Tom Carper, D-Del., was the only Democrat to vote with Republicans.

The White House downplayed the setback. “It is not unprecedented — to say the least — for the United States Senate to encounter procedural snafus,” said press secretary Josh Earnest prior to the vote as defeat looked likely.

As is almost always the case with these types of filibusters, broad Democratic support of the TPA could hinge on Republican support for a series of additional trade agreements:

But several Democrats say they will back fast track only if Republican leaders clear a path for three other trade measures. One, to renew the African Growth and Opportunity Act, is uncontroversial.

The second calls for Trade Adjustment Assistance, which provides federal aid to workers displaced by trade agreements. Republicans don’t like it, but reluctantly acknowledge it’s the price for winning even modest Democratic support.

The third bill, involving Customs enforcement, is the stickiest. It includes a measure to take actions against countries that keep their currency artificially low, which makes their exports more attractive. The Obama administration opposes the “currency manipulation” measure, saying it could invite international challenges to the Federal Reserve’s policies meant to boost the economy.

Some Democrats also want to force Republicans to deal first with a surveillance measure that Democrats consider more pressing. That strategy suggests Obama might have better luck on trade in a month or so.

The issue is bipartisan, but opposition is political. The White House wants this deal because it would allow the president the opportunity to sweeten perception of his final term; Democrats are afraid of it because labor unions have been lobbying furiously against anything that could broaden opportunities overseas and affect US jobs.

Love or hate the idea of a fast track on trade agreements, it has to warm your heart to see Obama’s own caucus throwing his agenda under the bus in favor of a blatantly political nod to destructive special interests.

UPDATE: Apparently we have a deal.

Via Politico Breaking News:

Senate leaders have reached a deal to move forward with fast-track trade legislation, a centerpiece of President Barack Obama’s economic agenda. The agreement calls for separate votes on several Democratic priorities, including a bill to help U.S. workers affected by expanded trade. The deal follows 24 hours of furious negotiating after the trade package failed in the Senate on Tuesday.