Joel Auerbach, Associated Press
Democratic National Committee Chairwoman, Rep. Debbie Wasserman Schultz, D-Fla., left, looks on as Vice President Joe Biden discusses the Iran nuclear deal with Jewish community leaders at the David Posnack Jewish Community Center in Davie, Fla. on Thursday, Sept. 3, 2015. Exploring a presidential campaign, Biden offered a robust defense of a nuclear accord with Iran strongly backed by the White House in the latest sign of his work to present himself as a natural heir to President Barack Obama.

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

Former Secretary of State Colin (KOH'-lihn) 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.