It took just a few hours for the new Republican-controlled Congress to elicit its first veto threat from President Obama, dashing initial hopes for bipartisanship and cementing the status of the Keystone XL pipeline as Washington's reigning political football.

To be sure, the president's opposition to a bill approving the project is hardly surprising given his past statements. But the decision to issue a formal veto threat this week underscores the raw politics that surround Keystone after six years of regulatory limbo.

The White House would only hint at a veto back in November, when the measure fell just one vote short of approval in the Democratic-led Senate as former Sen. Mary Landrieu eyed it as a possible political lifeline. Months later, the same Democratic leadership that allowed a vote on the Landrieu bill derailed a planned Senate Energy Committee hearing on the subject.

Still, despite obstacles at both ends of Pennsylvania Avenue, Keystone backers insist they will prevail in the end – it’s just a question of when and how. The House is set to consider Keystone Friday and the Senate energy panel voted 13-9 on Thursday to send its bill to the floor, with debate expected next week. 

Both the House and Senate have enough votes to send the bill to the president’s desk, but assembling a veto-proof majority would be a heavy lift.

“If we can’t override the veto, I think it’s pretty clear to the public and everybody else that the president is the obstructionist, not the Congress,” Rep. Kevin Cramer, a North Dakota Republican, told Fox News, citing polls that show overwhelming public support for building the pipeline.

In an exclusive interview Senate Majority Leader Mitch McConnell said on “The Kelly File” Thursday that a vote on the Keystone pipeline is his first order of business.

McConnell said it is “a decision [Obama’s] been sitting on for five years. It would put literally thousands of Americans to work very quickly.” He added that Obama is "controlled by the far-left environmental extremists in this country.”

In the last Congress, the GOP-controlled House passed a bill approving Keystone with 252 votes. While some Democrats are expected to join Republicans in voting for the measure when it hits the floor this time around, their 246-member strong caucus would need dozens of defectors to get to the 290 necessary to beat back a veto.

Keystone cheerleaders in the Senate face a similar uphill battle. While 60 senators are signed onto the bill and an additional three have said they will back it – enough to guarantee passage – supporters would need four more votes for a veto-proof majority.

Sens. John Hoeven, R-N.D., and Joe Manchin, D-W.Va., say they hope to pick up additional backers through an open amendment process that would allow colleagues to alter the bill. If they fall short, Hoeven acknowledged Congress may have to take a second bite of the apple by attaching Keystone to an appropriations bill or another “must-pass” piece of legislation.

Keystone XL is a proposed 1,179-mile extension of an existing pipeline, which owner TransCanada Corp. says would transport 830,000 barrels of crude oil a day from Alberta, Canada, to Nebraska. TransCanada filed its first permit application with the State Department in September 2008.

Opponents of the pipeline accuse backers of overestimating the project’s impact on the economy, arguing that the oft-cited figure of 42,000 jobs represents only temporary construction jobs. Beyond that, they say Canadian tar sands oil would have devastating effects on the environment.

“The tar sands flowing through the pipeline will result in pollution that causes serious illnesses like asthma and increases in carbon pollution – the main cause of climate change,” Sen. Barbara Boxer, a California Democrat and one of Keystone’s fiercest critics, said Tuesday.

For its part, the White House cited procedural reasons in its veto threat, saying legislation that would approve the project through Congress’ power to regulate interstate commerce nevertheless encroaches on its executive authority.

The legislation “conflicts with longstanding executive branch procedures regarding the authority of the president and prevents the thorough consideration of complex issues that could bear on U.S. national interests,” it said.

Keystone supporters knew a veto threat was a good possibility but say they were surprised to see one before the legislation even hit the floor.

“His decision to veto such a commonsense bill prior to the unfolding of regular congressional order and the offering of amendments appears premature and does little to mitigate the congressional gridlock,” Manchin said in a statement.

Capitol Attitude is a weekly column written by members of the Fox News Capitol Hill team. Their articles take you inside the halls of Congress, and cover the spectrum of policy issues being introduced, debated and voted on there.