Below the surface, Mr. Paul’s diagnosis prompted fear and anger inside the Capitol. Aides in the Kentucky Republican’s Washington office were anxious and outraged by the senator’s decision to continue working after learning he had potentially been exposed, without telling staff members who could have become infected, according to a person familiar with the situation who insisted on anonymity to describe internal discussions.

Two Republican senators who had dined with Mr. Paul left the Capitol and quarantined themselves as a precaution. And those left in the building on Monday were clearly uneasy as their impassioned pleas for action became freighted with a certain grim subtext…

The news that Mr. Paul had maintained his normal schedule for days after getting tested — dining with his colleagues at conference lunches, voting on the Senate floor and taking a swim in the senators-only pool just hours before he received his results — ricocheted through the Capitol, rattling and angering the network of lawmakers and aides who have worked late hours for days in close quarters, and plan to continue doing so for the foreseeable future.