The U.S. Senate approved a landmark immigration bill on Thursday that would provide millions of undocumented immigrants a chance to become citizens but the leader of the House of Representatives said the measure was dead on arrival in the House.

In a rare show of bi-partisanship, the Democratic-controlled Senate passed the bill by a vote of 68-32, with 14 of the Senate's 46 Republicans joining all 52 Democrats and two independents in support of the bill.

A packed gallery of supporters, who have labored decades for such a moment, witnessed the vote, which came after three weeks of sometimes heated debate.

They were fully aware that hours before the vote, House Speaker John Boehner reiterated that Republicans would "do our own bill," one that "reflects the will of our majority," many of whom oppose citizenship for immigrants who are in the United States illegally.

While a combined vote of House Democrats and Republicans could conceivably team up to pass the measure, Boehner repeated that he would not allow consideration of any measure that does not have the support of most of the House's 234 Republicans.

That position may make it impossible to pass a comprehensive immigration bill in this Congress, a top priority of Democratic President Barack Obama. (Additional reporting by Rachelle Younglai; Editing by Fred Barbash, Cynthia Osterman and Bill Trott)