Senate Republicans on Wednesday blocked a second attempt to quickly pass legislation aimed at protecting special counsel Robert Mueller from being fired without cause by President Trump.

Sens. Jeff Flake, R-Ariz., Chris Coons, D-Del., and Cory Booker, D-N.J., pushed the Senate to accept their legislation by unanimous consent. They and other senators worry that Trump could be on the verge of firing Mueller while he’s still in the process of investigating Trump’s alleged ties to Russia.