White House press secretary Josh Earnest told members of the news media Tuesday at the daily briefing that President Obama would veto a bill that allows for the construction of the Keystone XL pipeline. (WhiteHouse.gov)

The new Congress was not yet two hours old when the White House announced Tuesday that the president would veto the first bill lawmakers plan to send to his desk: a measure authorizing the construction of the Keystone XL pipeline across the Canada-U.S. border.

The veto threat — which White House press secretary Josh Earnest issued as a dozen new GOP senators took their oaths and House Republicans reelected John A. Boehner (Ohio) as speaker — marked a contentious start to a session during which the president will face a legislative branch controlled by the GOP.

Earnest couched the administration’s opposition to the project — which would transport heavy crude oil extracted in Hardisty, Alberta, to refineries on the U.S. Gulf Coast — in the narrowest possible terms, saying it was a matter of allowing the federal review process to take its course.

The State Department has completed an environmental assessment of the proposal by Trans­Canada, but it is waiting for the Nebraska Supreme Court to rule on whether the pipeline’s route through that state was properly considered before it issues a conclusion on whether the project would benefit the national interest.

“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. “I think the president has been pretty clear that he does not think that circumventing a well-established process for evaluating these projects is the right thing for Congress to do.”

Obama rejected an attempt by lawmakers two years ago to force his hand on the issue, vetoing a measure requiring him to make a final decision on the permit within a matter of weeks.

But even as Earnest said the administration “would withhold broader judgment on the project itself,” he emphasized that the president has described the pipeline’s announced potential benefits as exaggerated.

“The president did make clear that he was a little skeptical of the claims that are made by some of the most enthusiastic advocates of the pipeline’s construction, about the impact it would have on energy prices or on job creation,” Earnest said.

The project, which would carry a total of roughly 800,000 barrels of crude daily from Canada’s oil-sands region and the Great Plains’ Bakken formation, has become a litmus test in the broader debate over how to address climate change. Opponents argue that the pipeline will worsen global warming by accelerating the energy-intensive extraction of Canada’s bitumen deposits, and they say that much of the refined petroleum products will not remain in the country but eventually will be exported through the Gulf. Backers say the project will give construction workers jobs in the short term and maintain employment at American refineries over time, while ensuring a steady supply of oil from a U.S. ally.

While many lawmakers expect the president to veto the measure once it reaches his desk — the main Republican sponsor of the Senate bill, John Hoeven (N.D.), said in an interview that he was not surprised — the fact that the White House issued the threat before the bill had even reached the floor offended several of them.

“It’s the most discouraging thing I’ve ever heard,” Sen. Joe Manchin III (D-W.Va.) said in a phone interview minutes after Earnest made his comments. “For the leader of the country to say, basically, ‘Forget it. This is all for naught,’ is not what this country is about. It’s not what we’re all about, and it’s not the process that I’m used to working through.”

Manchin, who authored the bill with Hoeven, said he had called a senior official in White House legislative affairs Tuesday morning to discuss the proposal and had gotten no indication that Obama was ready to announce a veto threat.

“We had a very good talk. I just did not expect this to come back this soon,” Manchin said.

Republicans were even more scathing in their response. Senate Majority Leader Mitch McConnell (R-Ky.) noted in a statement that when then-Sen. Mary Landrieu (D-La.) “was trying to save her job over the exact same Keystone bill,” the president did not issue the same threat.

“The president threatening to veto the first bipartisan infrastructure bill of the new Congress must come as a shock to the American people, who spoke loudly in November in favor of bipartisan accomplishments,” McConnell added.

Sen. Richard J. Durbin (D-Ill.), who prompted the cancellation of a Wednesday hearing by the Senate Energy and Natural Resources Committee on the Keystone XL bill by objecting to it, said in an interview that when there are fundamental policy differences between the parties, “the question is whether 34 Democrats will stand with the president.”

“That’s the insurance policy,” Durbin said. “That’s the last card to play. I hope we don’t reach that very often, on this issue or any other.”

Asked whether Democrats can sustain a veto on Keystone, Durbin replied, “Based on the last roll call [in November], we do.”

It is unclear to what extent the fight over Keystone will spill over into other policy debates this year. Jack N. Gerard, president and chief executive of the American Petroleum Institute, noted that the Senate bill already has 60 co-sponsors and said that his group knows of three additional senators who support it.

Gerard said he remained confident the pipeline will eventually be approved, but Tuesday’s announcement “doesn’t bode well for relationships between the White House and Capitol Hill.”

Earnest, for his part, accused Republicans of playing politics with the vote: “Maybe it raises questions about the willingness of Republicans to actually cooperate with this administration when you consider that the very first bill that’s introduced in the United States Senate is one that Republicans know the president opposes.”

The administration has already permitted the construction of the pipeline’s southern leg, which runs 485 miles between Steele City, Neb., and Port Arthur, Tex. But the 1,179-mile northern leg between Hardisty and Steele City has been on hold for six years.

TransCanada president and chief executive Russell K. Girling expressed exasperation Tuesday at the long wait.

“The review process for Keystone XL has been anything but a ‘well-established process,’ ” he said in a statement. “For decades the normal process to review and make a decision on an infrastructure project like Keystone takes two years.”

Environmental groups such as the Natural Resources Defense Council, meanwhile, hailed the White House’s stand.

“The new Republican majority in Congress wants to play pipeline politics with our future, and the president is focused on a single question: Is the tar sands pipeline in our national interest?” said NRDC spokesman Bob Deans. “It’s not.”

Hoeven, who noted that the pipeline has broad support from the American public, said the fact that members of both parties would have an opportunity to amend the Keystone bill could give it political momentum. And even if lawmakers cannot override the president’s veto, he added, they would try to add it to another bill this year.

“I’ve always contended we’ll win on the merits, and I still think that’s the case,” Hoeven said. “I hope it helps us break through some of the partisanship and break through some of the gridlock.”

Lori Montgomery, Greg Jaffe and Paul Kane contributed to this report.