(ABCNEWS.GO) — Defying the Republican-run Congress, President Barack Obama rejected a bill Tuesday to approve construction of the Keystone XL oil pipeline, wielding his veto power for only the third time in his presidency.

Obama offered no indication of whether he’ll eventually issue a permit for the pipeline, whose construction has become a flashpoint in the U.S. debate about environmental policy and climate change. Instead, Obama sought to reassert his authority to make the decision himself, rebuffing GOP lawmakers who will control both the House and Senate for the remainder of the president’s term.

“The presidential power to veto legislation is one I take seriously,” Obama said in a brief notice delivered to the Senate. “But I also take seriously my responsibility to the American people.”

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