WASHINGTON — The Republican-controlled House passed legislation today approving the Keystone XL oil pipeline, setting the stage for a Senate showdown that mixes energy politics with a fight over Louisiana’s Senate seat.

The vote was 252-161 in favor of the bill, which was sponsored by Rep. Bill Cassidy, R-La., in an effort to boost his chances to take Louisiana’s Senate seat away from Democrat Mary Landrieu.

The two are headed for a Dec. 6 runoff and have been touting their energy credentials in their oil and gas-producing state.

Landrieu, who is facing an uphill battle to retain her seat, successfully pushed the Democratic-run Senate to hold a vote on the measure next week.

The bill was supported by 221 Republicans, and not a single GOP lawmaker voted against it. Thirty-one Democrats also backed the bill, while 161 rejected it.

The project has been stalled by environmental reviews, by objections to the route it would take and by politics for six years.

But the latest bid by House Republicans has the best chance of reaching President Barack Obama’s desk. While the White House has issued veto threats on similar legislation before, it had yet to do so today.

Advocates say it will create thousands of jobs and aid energy security, but environmentalists warn of possible spills and say the pipeline will expedite development of some of the dirtiest oil available.