By MATTHEW DALY

WASHINGTON — Already a done deal in Congress, the Iran nuclear agreement is gaining more momentum.

Former Secretary of State Colin Powell and Rep. Debbie Wasserman Schultz, who heads the Democratic National Committee, are backing it.

Powell secretary of state under President George W. Bush tells NBC’s “Meet the Press” that the agreement is “a pretty good deal” and would reduce the threat of Iran gaining a nuclear weapon.”

Wasserman Schultz calls her decision the most difficult she’s made in nearly 23 years in elected office.

The Florida lawmaker, who’s Jewish, writes in The Miami Herald that the deal “-provides the best chance to ensure” security for the U.S., Israel and other allies.

The White House has clinched the necessary Senate votes to ensure Congress will uphold the deal.