On the trail, James Talarico, the Democratic Senate nominee, has increasingly gone after Mr. Musk, a critic of his who has given big to a group aligned with the Republican candidate, Ken Paxton.
Senators have warned the White House they will withhold confirmation votes until the administration ensures the restoration of communications capabilities used by Ukraine’s military.
Representative Brian Fitzpatrick, Republican of Pennsylvania and a former F.B.I. agent who worked on Russian counterintelligence in Kyiv, said he doubted the communication problems were accidental.