Last night, US House majority leader Eric Cantor lost the Republican primary to a tea party challenger who painted Cantor as too willing to compromise with Democrats. Cantor’s loss makes this summer’s looming congressional fight over transportation funding all the more unpredictable.

US Highway Trust Fund balance. If Congress doesn’t act soon, money will run out. Image from USDOT.

MAP-21, the federal transportation funding bill, expires in October. But the US Department of Transportation (USDOT) will begin running out of money in August. Without a bipartisan bill to add new money, federal transportation funding will trickle to a halt.

Transportation wasn’t a major issue in Cantor’s election, but immigration reform was. Cantor mostly opposed immigration reform, but he briefly contemplated compromise, giving his more conservative opponent David Brat an opening to attack.

Some pundits fear that will push every other House Republican away from compromise in general, and grind whatever progress Congress was making on anything to a halt.

From an immigration perspective that probably makes little difference; House Republicans were not going to compromise anyway. But it could make a huge difference for transportation.

Transportation funding was a non-partisan issue in the 20th Century. Every six years Congress would pass a transportation bill with broad support from both parties. But in recent years, amid declining gas tax revenue and increasing need for supplemental funding, transportation has become a partisan spark.

Congress seemed primed to act, but now it’s an open question

Up until Cantor’s defeat, the general assumption in the transportation world has been that Congress would do something this summer. “Something” might mean a long term solution like a new bill and new taxes. Or it might mean a band-aid, like an extension of MAP-21 with an infusion of federal general fund dollars. Either way, Congress appeared to be making some progress.

But now? House Republicans might very well cease all legislative activity, and hope to ride out the rest of election season without upsetting their conservative base.

Polls show that raising money for transportation is popular, and voters rarely punish officials for doing so. But that may not matter to Republicans concerned about attacks from the extreme right.

While in Congress, Cantor fought against progressive transportation funding. But in this case his personal vote, and even his leadership on the specifics, might be less important than the simple fact that he was probably willing to advance a bill.

On the other hand, maybe the Republican establishment will take this as a call to arms, and moderate legislators will become more powerful. But that seems unlikely the day after the biggest tea party victory of the season.

Cross-posted at BeyondDC.