WASHINGTON — President Obama’s latest cabinet-level nominees are running into deep resistance in the Senate, pitching Democrats and Republicans into another tense standoff over White House appointments.

Just days after Republicans used Senate rules to block two nominees from moving to the next step in the confirmation process despite the fact that both have the support of a majority of senators, Democrats are planning to force committee votes without Republican consent.

If Democrats do push the nominees through to the full Senate, they would almost certainly set off a Republican filibuster, which would jeopardize the confirmations and, for now, leave vacancies at the top of two federal agencies.

Republicans have objected to the nomination of Gina McCarthy to lead the Environmental Protection Agency, citing what they said were her insufficient responses to their questions. They have also sought to block the labor secretary nominee, Thomas E. Perez, a lawyer in the Justice Department, on the grounds that he is too political.