“It’s very difficult to message on quicksand,” she said.
Problems for House Republicans surfaced almost as soon as the formal inquiry began, with a halting performance last weekend by Representative Kevin McCarthy, Republican of California and the minority leader, on CBS’s “60 Minutes.” Mr. McCarthy appeared not to have read the transcript of a call between Mr. Trump and the Ukrainian president that is at the heart of the impeachment inquiry; as he tried to defend the president, the correspondent Scott Pelley noted that he was reciting a set of talking points that the White House had circulated earlier.
Republican lawmakers and aides fretted privately that Mr. McCarthy looked unprepared and uncertain, and that their party had no strategy for confronting the crisis engulfing the president. Since then, leaders have buckled down to devise a fusillade of messages they hope will resonate with the public as the investigation unfolds.
An early version of their defense centered on three main arguments: that Democrats are truly trying to impeach the president, that nothing in Mr. Trump’s call with the Ukrainian president is impeachable and that Democrats are exploiting the call to achieve an end result they had hoped for from the beginning of Mr. Trump’s presidency, impeachment.
But in a sign of how Republicans’ strategy has continued to shift, Mr. McCarthy in recent days has appeared to adopt a number of other approaches, most notably introducing a message that focuses narrowly on Democrats’ impeachment process. That strategy hinges on the belief that voters will reject Speaker Nancy Pelosi’s decision not to hold a vote to start an impeachment inquiry. Republicans argued in a legal brief on Thursday that the House had not in fact begun a real impeachment investigation because it had not authorized one with a full vote.
The strategy tracks with one the White House has considered, as top officials weighed sending a letter to Ms. Pelosi to inform her that they would not comply with demands for documents or witnesses until the full House voted to formally open an impeachment inquiry. But on Friday, aides in the West Wing were reassessing the move, first reported by the website Axios, worrying that it might only draw out the impeachment process.
Borrowing a page from Democrats during the impeachment of President Bill Clinton, Republicans are also working to demonize the leaders of the inquiry. Mr. McCarthy is supporting a resolution by Representative Andy Biggs of Arizona, the chairman of the Freedom Caucus, to formally censure Representative Adam B. Schiff of California, the chairman of the Intelligence Committee, who has taken a leading role.
Mr. Scalise rallied his deputies during a call on Thursday afternoon, saying he would lead a series of all-conference member briefings moving forward, according to a person on the call who insisted on anonymity to describe it. Representative Steve Chabot of Ohio, a manager during the Clinton impeachment, outlined what lawmakers could expect in the weeks to come.
“What members really want are all the facts because there are a lot of allegations that have been thrown around,” Mr. Scalise said.