By Katharine Jackson

WASHINGTON (Reuters) - A gun-safety bill that marked rare bipartisan cooperation as it passed the U.S. Senate was poised for approval by the House of Representatives on Friday on its way to President Joe Biden's desk.

The Senate bill, passed in a 65-33 vote late Thursday, is a modest package of measures to toughen federal gun laws, weeks after mass shootings in Uvalde, Texas, and Buffalo, New York, that killed more than 30 people, including 19 children. Fifteen Republicans joined all 50 Senate Democrats in voting for passage.

It is the first major gun-control legislation to pass in three decades in a country with the highest gun ownership per capita in the world and the highest number of mass shootings annually among wealthy nations.

Democratic House Speaker Nancy Pelosi applauded the bill's passage and said in a statement that her chamber would take up the bill "first thing" on Friday, with a vote coming as soon as possible.

The legislation would tighten background checks for potential gun buyers with prior domestic violence convictions or significant juvenile criminal records as well as increase funding for school security and mental health programs.

House Republicans urged members to vote against it, but in a chamber controlled by Democrats, their support is not needed for passage.

Biden has said that he will sign the bill into law.

(Reporting by Katharine Jackson; Editing by Mark Porter)