Sen. Lindsey Graham (R-S.C.) said Thursday that he is writing a bill that will limit President Trump's ability to fire the special counsel investigating Russian election meddling.

Graham said his bill, which he will introduce next week, will block a president from firing the special counsel without a federal judge's approval if that counsel is investigating the president or his administration, according to The Wall Street Journal.

The South Carolina Republican has a Democratic cowriter on the legislation in Sen. Cory Booker (N.J.), who said on MSNBC earlier this week that he had "concerns" about Trump attempting to oust Robert Mueller.

"It has to be for cause and the judicial branch should have a say in whether there is legitimate cause or not," Booker said on Tuesday.

Graham said he was crafting the legislation because "we need a check and balance here" and that the bill will apply to Trump as well as all future presidents.

Trump has left the door open to firing Mueller, who is reportedly investigating his finances in addition to possible ties between Trump's campaign and Russia.

Deputy Attorney General Rod Rosenstein, who appointed Mueller, has said that he would not fire the special counsel if Trump asked him to. But if Trump fires Attorney General Jeff Sessions - whom he has repeatedly attacked for recusing himself from the Russia investigation - he could appoint a new attorney general, who in turn could fire Mueller.