Washington CNN —  

Senate Democratic Leader Harry Reid offered a public endorsement of President Barack Obama’s Iran nuclear deal on Sunday, giving the White House a boost in its bid to keep Congress from blocking the agreement’s implementation.

“I strongly support the historic agreement with Iran and will do everything in my power to ensure that it stands,” Reid tweeted.

He first told The Washington Post of his decision on Sunday. And Sen. Debbie Stabenow, D-Michigan, on Monday also announced her support for the deal saying that “the imminent threat of Iran having a nuclear weapon outweights any flaws I see in the international agreement.”

That means that the Iran nuclear deal is now backed publicly by 28 Democrats – with just two, New York Sen. Chuck Schumer and New Jersey Sen. Robert Menendez, opposing it.

That Democratic support is key, because Obama will need at least 34 senators to support the agreement in order to sustain a presidential veto of a Republican-driven effort to block the United States from dropping its sanctions on Tehran in exchange for changes to its nuclear program and increased international inspections.

If 41 Democrats support the deal, the party could hand Obama an even bigger victory by blocking a vote on the GOP-backed measure from taking place.

CNN’s Jeremy Diamond and Ted Barrett contributed to this report.