Two Republican senators signed on Tuesday to Sen. Claire McCaskill's (D-Mo.) campaign to end the Senate's practice of secret holds on nominees and legislation.

McCaskill's letter urging leaders to end the privileged holds gained two more Republican signatures: Olympia Snowe of Maine and Bob Corker of Tennessee.

McCaskill told The Hill Tuesday that Snowe and Corker have signed onto a letter she is drafting to Majority Leader Harry Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.) to change the rules that allow senators to block nominees and bills anonymously. The letter was previously signed by GOP Sens. Scott Brown (Mass.) and Susan Collins (Maine).

McCaskill said she is also negotiating with Sens. Chuck Grassley (R-Iowa) and James Inhofe (R-Okla.), both of whom support a resolution by Sen. Ron Wyden (D-Ore.) to end the practice. McCaskill said she will send the letter to Reid and McConnell once she collects 70 signatures. Sixty-seven votes are needed to change the rules.

The Hill reported Tuesday that of the 61 senators that support ending the practice of secret holds, three have non-secretive holds of their own, either on a nominee or a bill.