Many Republicans are gravitating toward a technical argument: The Senate lacks jurisdiction to try him after he leaves office, they maintain, because he will be a private citizen. That could allow the Republicans to thread a political needle, voting against Mr. Trump’s conviction without having to defend his conduct, people familiar with the discussions say…

If the framers did intend to expose former presidents to impeachment trials, they left some details unclear. For instance, while the Constitution specifies that the U.S. chief justice preside when the Senate tries the president, it is silent about who oversees an ex-president’s trial. (Chief Justice John Roberts, who oversaw Mr. Trump’s first Senate trial, declined to comment on a possible repeat appearance.)…

People familiar with Senate discussions say that several Republicans have consulted with Mr. Luttig, who also told Vice President Mike Pence that there was no constitutional authority to discard electoral votes cast for Mr. Biden before Mr. Pence announced on Jan. 6 that he would count the votes as certified by the states.