WASHINGTON -- The White House issued a veto threat Tuesday for pending legislation intended to force federal approval of the Keystone XL pipeline.

"The fact is this piece of legislation is not altogether different than legislation that was introduced in the last Congress," said White House press secretary Josh Earnest Tuesday afternoon, referring to a bill that was defeated in November . "And you would recall that we put out a Statement of Administration position indicating that the president would have vetoed [it], had that bill passed the previous Congress."

"I can confirm for you that if this bill passes this Congress, the president wouldnt sign it either," Earnest continued.

Earnest's remarks came at a press conference shortly after Sens. John Hoeven (R-N.D.) and Joe Manchin (D-W.Va.) introduced legislation that would force federal approval of the pipeline. The bill, the first of the new Senate, has 60 co-sponsors, including six Democrats . The House is slated to vote Friday on its own bill to approve the proposed pipeline.

Earnest's comments appeared to be aimed at this specific "piece of legislation," rather than at the idea of the pipeline itself. The phrasing suggests that the White House could endorse the measure if some of the amendments that have been proposed by Senate Democrats are attached.

But the White House has repeatedly balked at legislation that would force approval before the federal review process is complete.

"There is already a well-established process in place to consider whether or not infrastructure projects like this are in the best interest of the country," Earnest said Tuesday.

The administration is awaiting a decision from the Nebraska state Supreme Court on the validity of the pipeline's proposed route through the state. "Once that is resolved," said Earnest, "that should speed the completion of the evaluation of that project."

At the American Petroleum Institute's annual energy outlook event Tuesday afternoon, CEO Jack Gerard said he was "disappointed" by the White House veto threat.

"I believe it doesn't bode well for relationships between the White House and Capitol Hill," said Gerard. "[The pipeline] has broad, bipartisan support."

UPDATE, 2:15 p.m. -- Later in the briefing, Earnest erased any lingering doubts from those reading his words literally. Though he had said the president would not sign a bill authorizing Keystone, he wasn't implying that he would let that legislation dangle indefinitely in the legal ether. He was, indeed, saying that the president would veto the measure.

As for the principal reason for the veto, Earnest said it had more to do with procedure than policy, though the White House objected to both aspects.

"The concern that we have right now is principally on the idea that this piece of legislation would undermine what has traditionally been, and is, a well-established administrative process to determine whether or not this project is in the national interest," he said. "The fact is, a complete evaluation of that project cant be completed until this legal dispute about the route of the pipeline has been settled and we know what the final route of the pipeline actually looks like."

The administration, he said, was withholding "broader judgment on the project itself," although he added that "you can note our skepticism about some of the claims made by the most enthusiastic advocates of the pipeline."

Meanwhile, a spokesman for Senate Majority Leader Mitch McConnell accused President Barack Obama of inconsistency on the issue.

"Its interesting that when Sen. Landrieu was trying to save her job last year through a vote on this same bipartisan Keystone XL infrastructure bill, the president didnt threaten a veto," said McConnell spokesman Don Stewart. "Now that its about to pass with a strong bipartisan vote and support tens of thousands of jobs, he threatens a veto."

However, Obama did imply in November that he was prepared to veto the earlier bill if it made it to his desk.

"My position hasnt changed, that this is a process that is supposed to be followed," Obama said at the time .