(Mandel Ngan/AFP/Getty Images)

Tensions between the White House and congressional Republicans escalated Monday after 47 Republican senators sent a letter to Iran’s leaders intended to hinder the administration's efforts to reach a nuclear deal with the country.

The White House issued a sharp rebuke Monday night, with Vice President Joe Biden calling the tactic “beneath the dignity of an institution I revere.”

The letter, spearheaded by Sen. Tom Cotton, was signed by 47 Republican senators. Seven GOP senators did not sign. Here's who signed:

Signatories:
Richard Shelby (Ala.)
Jeff Sessions (Ala.)
Dan Sullivan (Alaska)
John McCain (Ariz.)
John Boozman (Ark.)
Tom Cotton (Ark.)
Cory Gardner (Colo.)
Marco Rubio (Fla.)
Johnny Isakson (Ga.)
David Perdue (Ga.)
Mike Crapo (Idaho)
Jim Risch (Idaho)
Mark Kirk (Ill.)
Chuck Grassley (Iowa)
Joni Ernst (Iowa)
Pat Roberts (Kansas)
Jerry Moran (Kansas)
Mitch McConnell (Ky.)
Rand Paul (Ky.)
David Vitter (La.)
Bill Cassidy (La.)
Roger Wicker (Miss.)
Roy Blunt (Mo.)
Steve Daines (Mont.)
Deb Fischer (Neb.)
Ben Sasse (Neb.)
Dean Heller (Nev.)
Kelly Ayotte (N.H.)
Richard Burr (N.C.)
Thom Tillis (N.C.)
John Hoeven (N.D.)
Rob Portman (Ohio)
Jim Inhofe (Okla.)
James Lankford (Okla.)
Pat Toomey (Pa.)
Lindsey Graham (S.C.)
Tim Scott (S.C.)
John Thune (S.D.)
Mike Rounds (S.D.)
John Cornyn (Texas)
Ted Cruz (Texas)
Orin Hatch (Utah)
Mike Lee (Utah)
Shelley Moore Capito (W.V.)
Ron Johnson (Wis.)
Mike Enzi (Wyo.)
John Barrasso (Wyo.)

Did not sign:
Lisa Murkowski (Alaska)
Jeff Flake (Ariz.)
Daniel Coats (Ind.)
Susan Collins (Maine)
Thad Cochran (Miss.)
Lamar Alexander (Tenn.)
Bob Corker (Tenn.)

An already heated battle between the White House and Republicans over negotiations to curtail Iran's nuclear program grew more tense when 47 Republican senators sent a letter to Iran designed to kill any potential deal. But is it treason? (Jason Aldag/The Washington Post)