Acting FBI Director Andrew McCabe told senators that there has been “no effort” to impede the bureau’s investigation of Russian interference in the election and any Trump campaign collusion.

“There has been no effort to impede our investigation to date,” McCabe said.

His comment came in response to a question by Sen. Marco Rubio (R-FL) about whether President Trump’s firing of former FBI Director James Comey has impacted the investigation in any way.

McCabe added, “Simply put, sir, you cannot stop the men and women of the FBI from doing the right thing, protecting the American people, and upholding the Constitution,” he said.

Democrats have accused Trump of firing Comey to stymie the investigation.

The Wall Street Journal reported that the FBI’s investigation had begun to pick up steam in the last few weeks, and Comey had asked for more resources from Deputy Attorney General Rod Rosenstein.

Justice Department spokeswoman Sarah Isgur Flores told the WSJ that Comey last met with Rosenstein on May 1 and “there was no discussion of resources or funds related to the Russia investigation at that meeting.”

Acting FBI Director Andrew McCabe told senators on Thursday that he could not confirm that such a request was made, but said such a request would have been made to Congress, not through the Justice Department.

“It’s not consistent with my understanding of how we request additional resources,” he said.