PHOENIX - We're still in the middle of counting the votes for who will fill Sen. Jeff Flake's seat next year after the Arizona Senator since 2013 said he will retire. 

But, the war of words between the soon-to-be-retired Flake and President Donald Trump continues. 

President Trump's squabbles with the late Arizona Sen. John McCain were well-documented as McCain's moderate, bipartisan approach to politics since Trump assumed office clearly bothered the sitting president. 

Trump has also been critical of moderate Republican, Sen. Flake for years.

Flake and McCain were both openly critical of President Trump's demeanor, a battle Flake has carried on since McCain's passing.

It escalated again when Sen. Flake was cautious about confirming Trump-nominated Supreme Court Justice Brett Kavanaugh in September. Flake delayed the Kavanaugh confirmation one-week to allow the FBI to investigate by saying he would only vote yes if there was a proper FBI investigation.

Now, Flake is speaking out, saying somebody needs to run against Trump in the 2020 GOP Presidential Primary.

Flake has not ruled out running against Trump in the primary, either, as rumors have swirled about a possible Flake run for president after he thrust himself into the national spotlight in delaying the Kavanaugh confirmation.

In an interview with Politico and The Hill, Flake said Friday he has not ruled out running. He also name-dropped a couple of Republicans he said would give Trump a "credible challenge" in 2020 in Ohio Gov. John Kasich and Nebraska Sen. Ben Sasse, who was also on the Senate Judiciary Committee during the Kavanaugh confirmation.

Kasich ran in the 2016 GOP primary, where he won just his home state of Ohio. 

Flake further had this to say about the state of the Republican Party: “I hope somebody does [run], just to remind Republicans what it means to be conservative and what it means to be decent. We’ve got to bring that back. You can whip up the base for a cycle or two but it wears thin. Anger and resentment are not a governing philosophy.” 

On whether Trump can win a re-election in 2020, Flake said it will depend if a there is a quality alternative on the Republican side and if the Democrats nominate a challenger that is too far left.