WASHINGTON, D.C.: Leading senators supported a congressional investigation Monday into US intelligence assessments that Russia interfered in the election, putting top Republicans on a collision course with incoming president Donald Trump. The potential showdown between Trump and Capitol Hill could become more contentious after the president-elect announces his pick for the critical secretary of state post on Tuesday, with key Republicans concerned over his expected choice, ExxonMobil chief executive Rex Tillerson. The president-elect has dismissed the intelligence reports about Russian interference as “ridiculous,” defying an increasing number of senators from his own party, as well as top Democrats, the Central Intelligence Agency and the outgoing White House. US media have reported for days on secret CIA findings that Moscow sought to bolster Trump’s election bid, against Democratic former secretary of state Hillary Clinton, by releasing hacked Democratic Party documents. A group of 10 electors who will ratify the election results next week — all but one of them Democrats — also called for a full briefing on the accusations before the 538-member Electoral College gathers on December 19.