President Obama has been calling Republican and Democratic senators on Tuesday to discuss the gun-control vote, a White House official said.

Obama is expected to reach out to between half a dozen to a dozen senators in all, the official said.

The White House would not provide the call list, so it’s unclear whether Obama is reaching out to Republican senators who have promised to filibuster gun-control legislation.

One of the seantors to speak with Obama was Sen. Mark Kirk (R-Ill.). Kirk wrote on Twitter that he “had a good conversation” with the president about North Korea and background checks for gun sales.