Flake on chaos of Trump campaign: 'Was that campaign even capable of colluding with anybody?'

Frequent Trump administration critic Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeTrump suggests Heller lost reelection bid because he was 'hostile' during 2016 presidential campaign Live coverage: Trump delivers State of the Union Sasse’s jabs at Trump spark talk of primary challenger MORE (R-Ariz.) on Sunday said he's unsure if the Trump campaign was "capable of colluding with anybody."

"I mean, I look at that last campaign, and think 'was that campaign even capable of colluding with anybody?' It was so chaotic and whatnot," Flake said on ABC News's "This Week."

"But the problem is, as they always say, the cover-up and the sensitivity that the White House has to the special counsel and this investigation is troubling," he added.

ADVERTISEMENT

Mueller is investigating possible collusion between President TrumpDonald John TrumpBill Kristol resurfaces video of Pence calling Obama executive action on immigration a 'profound mistake' ACLU says planned national emergency declaration is 'clear abuse of presidential power' O'Rourke says he'd 'absolutely' take down border wall near El Paso if he could MORE's campaign and Russia. His probe has led to two indictments and two guilty pleas thus far.

Former Trump campaign chairman Paul ManafortPaul John ManafortThe Hill's 12:30 Report — Presented by Kidney Care Partners — Lawmakers scramble as shutdown deadline nears CNN's Toobin: 'Almost unrecognizable' Manafort 'in danger of losing his life' in prison The Hill's Morning Report - Presented by the American Academy of HIV Medicine - Will there be any last-minute shutdown drama? MORE and his former associate, Richard Gates, pleaded "not guilty" to charges of tax fraud and money laundering, among other things. Former national security adviser Michael Flynn and former Trump campaign aide George PapadopoulosGeorge Demetrios PapadopoulosDrama hits Senate Intel panel’s Russia inquiry Fox & Friends host says program will ‘absolutely’ accept Mueller report findings Source of Steele dossier info sought access to Trump allies in 2016: report MORE pleaded guilty to lying to the FBI.

Some Republican lawmakers have in recent weeks alleged bias within Mueller's investigation after it was revealed he removed an FBI agent from his team who allegedly sent anti-Trump text messages.

Trump has said he is not considering firing Mueller, but has lashed out at the FBI in recent days.

Flake said Sunday he "doesn't get caught up" in discussions over possible impeachment, but said it would be a "big problem" if Trump fired Mueller or pardoned Flynn.

"If the president continues to try to undermine the legitimacy of that investigation and if Republicans continue to try to help with that, I think that puts us in peril, that we shouldn't participate in the undermining of our institutions that way," Flake said.