President Obama vetoed the Keystone XL pipeline bill on Tuesday, Feb. 24, 2015. (AP Photo/Evan Vucci)

For just the third time since taking office, President Barack Obama vetoed a bill that came across his desk, this time to prevent the Keystone XL oil pipeline from moving forward.

“The Presidential is one I take seriously. But I also take seriously my responsibility to the American people,” he wrote in a message to the Senate. “Because this act of Congress conflicts with established executive branch procedures and cuts short thorough consideration of issues that could bear on our national interest — including our security, safety and environment — it has earned my veto.”

Obama vetoed the bill in private with no fanfare, in contrast to the televised ceremony Republican leaders staged earlier this month when they signed the bill and sent it to the president. House Speaker John Boehner, R-Ohio, said Republicans were “not even close” to giving up the fight and derided the veto as a “national embarrassment.”

Republican lawmakers say this likely won’t be the last time Obama takes this approach with the GOP-led Congress. “He’s looking at this as showing he still can be king of the hill, because we don’t have the votes to override,” Republican Sen. Jim Inhofe of Oklahoma, a vocal opponent of Obama’s climate change agenda, said in an interview. “If he vetoed this, he’s going to veto many others that are out there.”

The 875-mile Keystone XL pipeline has been polarizing since TransCanada’s original 2008 proposal. “The pipeline would transfer (about half of what the U.S. currently imports from the Middle East) and would create some 42,000 jobs, according to the House Energy and Commerce Committee,” we reported at the end of 2014. “ counter by saying that type of oil the pipeline would carry — from the Alberta tar sands — is one of the dirtiest around and that more jobs would actually be lost than created. They also express concern for the wildlife in the path of the pipeline.”

Republican leaders were mulling a number of potential next steps. In addition to trying to peel off enough Democrats to override Obama’s veto — an unlikely proposition — Republicans were considering inserting Keystone into other critical legislation dealing with energy, spending or infrastructure in hopes that Obama would be less likely to veto those priorities, said North Dakota Sen. John Hoeven. “We’ll look to see if we can get some more bipartisan support.”

Obama last wielded his veto power in October 2010, nixing a relatively mundane bill dealing with recognition of documents notarized out of state. With Keystone, Obama’s veto count stands at just three — far fewer than most of his predecessors. Yet his veto threats have been piling up rapidly since Republicans took full control of Congress, numbering more than a dozen so far this year.

The president has said he won’t approve Keystone if it’s found to significantly increase U.S. emissions of carbon dioxide, the chief greenhouse gas blamed for global warming. A State Department analysis found that the tar sands would be developed one way or another, meaning construction of the pipeline wouldn’t necessarily affect emissions. The Environmental Protection Agency earlier this month called for that analysis to be revisited, arguing that a drop in oil prices may have altered the equation.

The Associated Press contributed to this report.