WASHINGTON — Call it the two birds, one tweet approach: As he continues to feud with Senator Bob Corker, President Trump is now also blaming the Tennessee Republican for the Iran nuclear deal that the White House is threatening to decertify, perhaps as soon as this week.

But it is a misleading charge: Mr. Corker, who is chairman of the Senate Foreign Relations Committee, repeatedly spoke out against the accord to limit Tehran’s nuclear program before it was brokered by world powers in 2015.

“Bob Corker gave us the Iran Deal, & that’s about it,” Mr. Trump tweeted on Sunday.

On Tuesday, the White House offered details. “Senator Corker worked with Nancy Pelosi and the Obama administration to pave the way for that legislation, and basically rolled out the red carpet for the Iran deal,” Sarah Huckabee Sanders, the White House press secretary, told reporters, referring to the House Democratic leader.

She was talking about a bill that Mr. Corker sponsored and pushed through in the spring of 2015 to give Congress some say over the deal, as Republicans demanded at the time.