Representative Trey Gowdy (R-S.C.), during an appearance on "Fox News Sunday," had some strong advice for John Dowd, an attorney of President Donald Trump's who has called for an end to special counsel Robert Mueller's investigation into Russian interference.

"If you have an innocent client, Mr. Dowd, act like it," Gowdy said. "The President's attorney frankly does him a disservice when he says that."

Gowdy was responding to criticism of Mueller that the president tweeted over the weekend.

"Why does the Mueller team have 13 hardened Democrats, some big Crooked Hillary supporters, and Zero Republicans? Another Dem recently added...does anyone think this is fair? And yet, there is NO COLLUSION!" the president wrote yesterday, in yet another attempt to discredit the Russia investigation.

Mueller's investigation isn't limited to possible Russian collusion with the Trump campaign, Gowdy noted, adding that the investigation is also examining Russian interference with the entire U.S. democratic process and the 2016 presidential election.

"If the allegation is collusion with the Russians, and there is no evidence of that, and you are innocent of that, act like it," Gowdy said.

Gowdy, who is chairman of the House Oversight Committee and sits on the Intelligence and Judiciary committees, added later, "If you've done nothing wrong, you should want the investigation to be as fulsome and thorough as possible."

Gowdy wasn't alone in his criticisms. Senator Lindsey Graham, another prominent South Carolina Republican, addressed possibilities that the president could fire the special counsel during an interview on CNN.

"As I said before, if he tried to do that, that would be the beginning of the end of his presidency," Graham said on CNN's "State of the Union," adding that, despite Trump's criticisms, Mueller is doing "a good job."

I think it's very important he be allowed to do his job without interference and there are many Republicans who share my view," Graham said. "The only reason Mr. Mueller could ever be dismissed is for cause. I see no cause when it comes to Mr. Mueller."

He continued: "I pledge to the American people as a Republican, to ensure that Mr. Mueller can continue to do his job without any interference."

This isn't the first time Gowdy has called out the president for his behavior, namely his attempts to vindicate himself of anything related to the Russia investigation.

As recently as last month, Gowdy said the much-debated Nunes memo, which alleges abuses of covert surveillance powers by the FBI, does not vindicate Donald Trump, and that it will not have “any impact on the Russia probe.”

Gowdy made the comments while speaking to CBS’s Margaret Brennan during an appearance on Face the Nation.

“I actually don’t think it has any impact on the Russia probe for this reason––” Gowdy said.

“The memo has no impact on the Russia probe?” Brennan interjected.

“No— not to me, it doesn’t — and I was pretty integrally involved in the drafting of it. There is a Russia investigation without a dossier. So to the extent the memo deals with the dossier and the FISA process, the dossier has nothing to do with the meeting at Trump Tower,” Gowdy said. “The dossier has nothing to do with an email sent by Cambridge Analytica. The dossier really has nothing to do with George Papadopoulos’ meeting in Great Britain. It also doesn’t have anything to do with obstruction of justice. So there’s going to be a Russia probe, even without a dossier.”

The Nunes memo has fueled suggestions from members of the far right that the “rumor” of the Trump administration’s collusion with Russian operatives first began to make waves after Hillary Clinton’s campaign commissioned the now infamous dossier––as part of its own collusion with the FBI. In fact, that suggestion mischaracterizes the dossier. Its existence is significantly more complicated than that.

President Trump has continued to insist that the controversial dossier containing allegations of collusion with the Russian government compiled by former British intelligence agent Christopher Steele was not just “disproven” but “paid for by Democrats.” In January, Senator Dianne Feinstein (D-CA) released the unclassified transcript of the interview last August by Judiciary Committee members with Glenn Simpson, a founder of the research firm Fusion GPS, which the Clinton campaign retained to do opposition research on Trump. Simpson’s testimony indicates that Steele was so disturbed by his discoveries that he chose to alert the FBI.

Steele was initially hired to gather opposition research (something all campaigns do) about Trump for a Republican client. Steele alerted authorities when the information he received from a network of Russian sources described Trump’s business relationships with wealthy Russians and alleged ties to the Kremlin. The information came from two sources who spoke on condition of anonymity, citing the sensitivity of the matter.

Steele had worked with the FBI before and was well regarded. He presented the bureau with information in July and in September 2016 suggesting collusion between Trump’s associates and Moscow in the DNC hack. He later met with an FBI official in Italy to share information alleging that a top Trump campaign official knew about the hacking as early as June 2016. A month after the election, Senator John McCain (R-AZ) gave former FBI Director James Comey a copy of Steele’s reports.

The president used the memo’s release as an opportunity to once again discredit the Russia probe, and continued to insist that the memo’s release proves his innocence. “The memo totally vindicates ‘Trump,’ in the probe,” he wrote last month, referring to himself in the third person.