Senator Cory Gardner of Colorado, known as a talented campaigner, abruptly walked away from a filmed interview last weekend to avoid answering a question about the military assistance Mr. Trump withheld from Ukraine, a central issue in the inquiry into whether the president enlisted a foreign government to smear his political opponents. In brisk dashes back to their offices, Senators Martha McSally of Arizona and Joni Ernst of Iowa, quickly pivoted to other issues such as rising health care costs, border security and the trade deal with Mexico and Canada. And Senator Susan Collins of Maine has rebuffed any effort to get her to weigh in on impeachment, saying that doing so could jeopardize her impartiality as a juror in an increasingly inevitable trial of the president…

Mr. McConnell has instructed fellow Republicans privately that they must figure out individually the impeachment message that works best for them politically. But he is also keenly focused on tailoring the process to insulate his most vulnerable members from a constituent backlash. The resolution introduced on Thursday was in part an effort to allow Republicans to unite publicly behind a measure critical of the inquiry, a way to show the party base that they were behind Mr. Trump even as they refrained from defending his actions…

Some endangered Republicans have also carefully eyed blueprints tested by senators considered to be among the savviest in the conference. Senators Rob Portman of Ohio and Pat Toomey of Pennsylvania, have offered one alternative: staking out the position in interviews with local publications that while Mr. Trump’s call with President Volodymyr Zelensky of Ukraine may have been inappropriate, it is not impeachable.