By Patricia Zengerle and Richard Cowan
WASHINGTON, April 9 (Reuters) - U.S. House of Representatives Republicans on Thursday blocked a Democratic effort to end U.S. attacks on Iran, as Donald Trump's party continued to prevent efforts to rein in the Republican president's war powers.
Representative Chris Smith, a New Jersey Republican, presided over an abbreviated "pro forma" House session, ending it before a group of Democrats could seek to pass the resolution via unanimous consent.
Democrats in the Senate and House of Representatives have tried and repeatedly failed in recent months to pass war powers resolutions to force Trump to obtain lawmakers' authorization before launching military operations, in both Venezuela and Iran.
Trump's threat early this week that "a whole civilization will die" intensified concern from Democrats, dozens of whom called for Trump's removal from office. The 1949 Geneva Conventions on humanitarian conduct in war prohibit attacks on sites considered essential for civilians.
"Threatening genocide is not a negotiating tactic," Representative Sara Jacobs, a California Democrat, told a news conference outside the Capitol after the pro forma session, held because Congress is out of Washington for the two-week Easter recess.
Trump announced that he had agreed to a ceasefire in the U.S.-Israel war on Iran on Tuesday, less than two hours before his deadline for Tehran to reopen the blockaded Strait of Hormuz or face devastating attacks on its civilian infrastructure.
The White House says Trump's actions are legal and within his rights as commander-in-chief to protect the U.S. by ordering limited military operations.
Iran says its nuclear program is peaceful. The Trump administration has sought to portray the war as a decisive victory, although the top U.S. general said U.S. troops stood ready to resume fighting.
Trump's fellow Republicans hold slim majorities in both the Senate and House, and have almost unanimously backed all of his policies.
Although the U.S. Constitution says that Congress, not the president, can declare war, that restriction does not apply for short-term operations or if the country faces an immediate threat.
(Reporting by Patricia Zengerle, editing by Deepa Babington)
