President Donald Trump on Tuesday vetoed a resolution to end U.S. support of Saudi Arabia’s military campaign in Yemen, which has been blamed for tens of thousands of deaths in the region.

“This resolution is an unnecessary, dangerous attempt to weaken my constitutional authorities, endangering the lives of American citizens and brave service members, both today and in the future,” Trump said in a statement accompanying his veto.

The Senate passed the resolution by a slim majority in March, and the House did the same earlier this month. It was a rare use of the War Powers Resolution of 1973, which gives Congress the power to remove military forces from a conflict for which there’s been no formal declaration of war.

The measure was passed by a bipartisan group of senators, including seven Republican senators who broke ranks with their party leaders. Senate Majority Leader Mitch McConnell (R-Ky.) had urged lawmakers to reject the resolution at the time, saying it was “inappropriate and counterproductive.”

The veto was Trump’s second of his administration. He issued his first last month, blocking Congress’ attempt to end a “national emergency” declaration meant to obtain funds to build a wall along the southern border.

The move on Tuesday drew a quick backlash of rebukes, including from Sen. Bernie Sanders (I-Vt.), who has long been critical of the Yemeni conflict.

“I am disappointed, but not surprised, that Trump has rejected the bi-partisan resolution to end U.S. involvement in the horrific war in Yemen,” Sanders, who is running for the Democratic nomination for president in 2020, said in a statement. “The people of Yemen desperately need humanitarian help, not more bombs.”

House Speaker Nancy Pelosi (D-Calif.) lambasted the president, saying he had “cynically chosen to contravene a bipartisan, bicameral vote of the Congress.”