Republicans and Democrats in Congress don’t trust President Donald Trump, especially when it comes to all things Russia.

Several Republican and Democratic senators on Thursday introduced competing pieces of legislation with the goal of restricting Trump’s power to fire special counsel Robert Mueller, who’s leading the investigation into the Trump campaign’s possible coordination with Russia to win last year’s presidential election. The bills come on the heels of Trump (grudgingly) signing a bill that also limits his power to roll back sanctions against Russia for meddling in the election.

One of the bills introduced Thursday, The Special Counsel Integrity Act, would ensure that no Trump appointee can unilaterally change existing Justice Department regulations that only allow a special counsel to be fired with good cause. The bill would also allow any terminated special counsel to challenge their dismissal before a three-judge panel, which would have to make a determination in the case within two weeks. The bill is retroactive to the date of Mueller’s appointment, suggesting it was drafted with Trump in mind.

Democratic Sen. Chris Coons of Delaware and Republican Sen. Thom Tillis of North Carolina — as reliable a Republican as there is — introduced the bill with two other Democratic co-sponsors, Sen. Richard Blumenthal of Connecticut and Sen. Sheldon Whitehouse of Rhode Island.

In a separate attempt to protect Mueller from Trump, Republican Sen. Lindsey Graham of South Carolina and Democratic Sen. Cory Booker of New Jersey also introduced their own bill, the Special Counsel Independence Protection Act. It’s similar to the first bill except that the attorney general would have to get a three-judge panel’s approval to fire a special counsel beforehand instead of allowing a special counsel to challenge his dismissal after.

In light of the competing bills, Graham and Tillis indicated they would work together over the next few weeks to put forward a single proposal in September that would put some type of judicial check on the president. It’s about “asserting Senate power where it has waned over the past 70 years,” Tillis said on CNN Thursday.

The legislative branch has been asserting itself quite a bit in the Trump era even though the president’s own party controls both chambers. These new bills come just one day after it became law that Trump could no longer unilaterally roll back sanctions against Russia. That bill passed with such overwhelming bipartisan majorities that Trump reluctantly signed it. If he had vetoed it, Congress had signaled their willingness to rebuke him and override it.

Russian Prime Minister Dmitry Medvedev taunted Trump for signing the legislation.

The recent bipartisan concern over Mueller stems from weeks of angry criticism from the Trump administration over the investigation. Trump tweeted on June 15:

Those “bad and conflicted people” include Mueller who Trump has complained is too close to former FBI Director James Comey. “Well, he’s very, very good friends with Comey, which is very bothersome,” Trump told Fox and Friends in an interview aired on June 23.

The Trump team has gone so far as to argue that the entire special counsel investigation was launched on a fraudulent premise.

“The basis upon which this entire special counsel investigation is taking place is based on what?” Trump lawyer Jay Sekulow said on Meet the Press on July 16. “Illegally leaked information that was a conversation of the President of the United States with the then-FBI director and that is to me problematic from the outset, and I think that raises very serious legal issues as to the scope and nature of what really could take place.”