Republican campaign officials said they were urging senators to focus on the crisis, rather than shift into campaign mode.
“The only guidance we have is be a senator,” said Kevin McLaughlin, executive director of the National Republican Senatorial Committee. “Stay in touch with people, be a point of reference, just go do your job.”
The Senate website of Mr. Daines, who had hoped to escape a contest with Mr. Bullock, reflects that approach. It features a compilation of favorable video clips from Montana news outlets about Mr. Daines’s role in the coronavirus aid legislation — including a White House shout out from Vice President Mike Pence — under the headline “Sen. Daines is fighting for Montana on Covid-19 ” Also prominent were releases about benefits he had pushed, including a timeline of his role.
Some analysts said they were skeptical that Senate incumbents would receive a bounce from the legislative package. Mr. Gonzales suggested that even in this extraordinary environment, the battle for control of the Senate would come down to the public perception of Mr. Trump.
“In the end, I expect voters to fall back to their partisan corners and the most competitive Senate races will be significantly impacted by the president’s standing,” he said.
Democrats are counting on that as well, pointing to public unhappiness with the president’s response.
“In this evolving crisis, people want reliable information and steady leadership,” said Lauren Passalacqua, a spokeswoman for the Democratic Senatorial Campaign Committee. “Democrats are focused on solutions to address the spread of coronavirus and mitigate its impact on their states, sharing resources, hosting virtual town halls with experts and working to support their communities.” One thing both sides agree on is that even given the stakes in the fight for congressional control, campaigning is hardly uppermost in anyone’s mind at the moment.
“We have to deal with this,” Mr. McLaughlin, the head of the Senate Republican campaign group, said of the pandemic. “If we don’t fix this, it just doesn’t matter.”
Nicholas Fandos and Catie Edmondson contributed reporting.