With gas prices making American wallets a lot lighter these days, Democrats in congress up for re-election are realizing the millstone that Obama has placed around their necks by opposing the Keystone oil pipeline.

And they are abandoning their party leader on the issue in droves.

Byron York:

While much of the political world obsesses over Twitter fights and Seamus the dog, Barack Obama has set himself up for a high-profile defeat on one of the most important issues of the campaign.

The president has put his feet in cement in opposition to the Keystone oil pipeline. But on Capitol Hill, more and more Democrats are joining Republicans to force approval of the pipeline, whether Obama wants it or not.

The latest action happened Wednesday, when the House passed a measure to move the pipeline forward. Before the vote, Obama issued a veto threat. The House approved the pipeline anyway -- by a veto-proof majority, 293 to 127. Sixty-nine Democrats abandoned the president to vote with Republicans. That's a lot of defections.

When the House voted on the pipeline in July of last year, 47 Democrats broke with the president. Now that it's an election year and the number is up to 69, look for Republicans to hold more pipeline votes before November. GOP leaders expect even more Democrats to join them.

Then there is the Senate. Democrats are using the filibuster to stop the pipeline, which means 60 votes are required to pass it. (Some Democrats who bitterly opposed the filibuster when Republicans used it against Obama initiatives are notably silent these days.) In a vote last month, 11 Senate Democrats stood up against Obama to vote in favor of the pipeline. Add those 11 to the Republicans' 47 votes, and the pro-pipeline forces are just a couple of votes away from breaking Harry Reid's filibuster.

"We're right around the corner from actually passing it," says a well-informed Senate source. "Two-hundred-ninety-three votes in the House is a gigantic number. People want this thing."

If the environmental lobby wants to take Obama over a cliff, that's one thing. But the potency of Keystone as a campaign issue along with Obama's relative unpopularity in many red states where a Democrat is running for re-election has many Democrats nervous about the GOP making use of the issue.

The odds are pretty good that congress will send a pipeline bill to the president before the election. He will then have to decide whether to sign it, thus angering the greens, or veto it, thus angering everyone else.

Either way, it will be a big loss for the president.