Sen. Mitt Romney says he's "sickened" by the dishonesty the Russia investigation found in the Trump White House, but the president fires back that Romney should have put the same energy into running for president in 2012 that the Utah Republican has tapped in criticizing him.

Romney also tweeted Friday that in reading the special counsel's report he was "appalled" Americans working on the Trump campaign had welcomed help from Russia.

Read more: Seth Rich cleared of WikiLeaks' accusation and other things you may have missed in the Mueller report | Top Democrat slams Trump over Libya: Supporting an 'authoritarian attacking a UN-backed government'

On Saturday, Trump responded via Twitter, saying if Romney "spent the same energy fighting Barack Obama as he does fighting Donald Trump, he could have won the race (maybe)!"

In 2012 Romney won a slightly greater percentage of the popular vote than Trump in 2016. He's one of the few prominent Republicans to criticize Trump since Trump's election.

Former Arkansas Governor Mike Huckabee also slammed Romney for his statement. Huckabee, the father of White House Press Secretary Sarah Huckabee Sanders, wrote, "Know what makes me sick, Mitt? Not how disingenuous you were to take @realDonaldTrump $$ and then 4 yrs later jealously trash him & then love him again when you begged to be Sec of State, but makes me sick that you got GOP nomination and could have been @POTUS."

Huckabee Sanders has been under fire for misleading the public during her time as press secretary, with specific instances being documented in the Mueller report.