House Speaker Paul Ryan said Tuesday that special counsel Robert Mueller should be allowed to proceed in his investigation of Russia's election meddling, and said he'd advise President Trump not to fire him, a step some of Trump's close allies have said he is considering.

"I'd be surprised if he did that," Ryan, R-Wis., said on the Hugh Hewitt Show Tuesday. "I think he should let Bob Mueller do his job, do his job independently, and do his job quickly, because I think that that's what he would want to have happen."

Ryan spoke a day after several of Trump's allies said it's time to reconsider whether Mueller is the right person for the job.

Former House Speaker Newt Gingrich noted that Mueller has hired lawyers who have donated money primarily to Democrats, and said that means it's time to "rethink" whether Mueller can do the job objectively.

Democrats quickly warned that it would be a mistake for Trump to fire Mueller, and Ryan agreed.

"I think we should let Bob Mueller do his work and get to the bottom of it, and get to the bottom of it quickly so that he can be vindicated, get to these things," he said. "Let's not forget what this is originally all about. Russia is up to no good. Russia is trying to meddle into our elections."

While Democrats have been pushing for evidence that Trump conspired with Russia to change the outcome of the election, several Democrats have admitted that so far, there is no evidence of collusion.