WASHINGTON — Senator Ted Cruz, the sometimes-incendiary Texan running for the Republican presidential nomination, took to the Senate floor on Friday to call his party’s majority leader a liar in an extraordinary public airing of grievance.

Mr. Cruz, an ardent opponent of the federal Export-Import Bank, reacted in starkly personal terms after the leader, Senator Mitch McConnell, Republican of Kentucky, allowed a vote pressed by a bipartisan group of senators to resurrect the government’s export credit agency.

That vote will come Sunday in a rare weekend session of Congress called to rush forward a major infrastructure bill before the Highway Trust Fund runs out of money July 31.

“I cannot believe he would tell a flat-out lie,” Mr. Cruz said of Mr. McConnell, who he said had promised him there was no deal to bring the Export-Import Bank matter up for a vote.