Former Massachusetts Gov. Mitt Romney says he is "disappointed" in Sen. Harry Reid and is happy to see him leaving the Senate.

Reid, then Senate majority leader, took to the Senate floor during the 2012 presidential election and heavily implied that Romney, then the GOP presidential nominee, had not paid income tax for a decade.

Reid offered no evidence for the claim, but said the burden was on Romney to prove otherwise.

"Well, he surely went over the line," Romney said when asked about Reid on "Fox News Sunday"  this week, where he also slammed Hillary Clinton ahead of her formal announcement that she's seeking the Democratic nomination for president. 

"I'm disappointed in Harry Reid," Romney said. "That's really not appropriate for someone in his position to make unsubstantiated claims."

Reid made news again late last month when asked by CNN  whether he did the right thing in making he accusation.

"He didn't win, did he?" Reid said.

When asked again by Fusion  last week, Reid said he had no regrets at all. Reid was interviewed after announcing he will not seek re-election to his Nevada Senate seat.

Addressing Reid's impending retirement, Romney said the Senator was effective in his party, but "terribly ineffective" in pursuing a positive agenda for America.

"I'm glad he's retiring. I wish him well in his retirement, but I'm glad he's not in the Senate soon," Romney said.

As to the tax issue, Romney said he wishes he could go back and pay no taxes as Reid had claimed, "but the truth is I paid a lot of taxes."

He noted that he did publicly release his tax returns.

"Harry, I guess, just isn't big enough to admit it," he said.

Turning to Sunday's expected announcement of a presidential bid by former Secretary of State Hillary Clinton, Romney said Clinton is a "creature of Washington" who doesn't offer any new blood.

"She's been there a long time," he said, pointing to Clinton's comment she hasn't driven a car in18 years because she has been driven by Secret Service and other security.

Besides, he said, "Hillary Clinton is just not trustworthy."

Clinton's story of erasing all her emails from her time as secretary of state is making people remember that "with the Clintons it's always something," he said.

Her real challenge, he said, will be trying to run away from foreign policy.

"The Clinton-Barack Obama foreign policy has really been a bust," he said.

Though several members of Romney's 2012 staff now are working for Florida Sen. Marco Rubio, who is expected to announce his presidential campaign on Monday, Romney said he has a "soft spot" for almost all the GOP candidates.

Republicans will have an "exciting debate," he said. As for the Democrats, he added, it "looks like it's going to be pretty quiet over there."