After a widely victorious night of Tuesday primaries, former Vice President Joe Biden widened his lead as the frontrunner in the Democratic race to take on President Donald Trump in November.

Biden won Mississippi, Missouri, and the night's biggest prize, Michigan.

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With Biden's campaign fully revived, it's no wonder that President Donald Trump and his allies in Congress are once again looking to smear Biden and his son Hunter for Hunter's board position at a Ukrainian energy company.

Former Senator Claire McCaskill (D-MO) was quick to call out one of her former colleagues, Senator Ron Johnson (R-WI) for using his position as the Senate Homeland Security Committee Chairman to investigate the Bidens when there are a number of more urgent issues for the committee to address.

As MSNBC's Morning Joe panel discussed the growing coronavirus threat, McCaskill pointed out that Johnson is more concerned with the Bidens than with the outbreaks of coronavirus.

She didn't mince words, saying:

"Allow me to pop off on Ron Johnson here. What a joke! What an embarrassing tool! He is chairman of the Homeland Security Committee! Right? He has jurisdiction over coronavirus and the federal response. Is he calling a hearing? Is he trying to figure out why first responders' tests aged on a shelf in the state of Washington until they were no longer good? Is he going to tell people why they can't get the test? No."

She wasn't done.

"Even though it's not in his committee's jurisdiction — the Judiciary Committee is not issuing subpoenas on Hunter Biden. The Foreign Affairs Committee is not issuing subpoenas on Hunter Biden. No! This joke, Ron Johnson, is actually politicizing a committee that right now should have one focus: What is going on with the United States of America's federal response to the coronavirus? People should be really angry about this."

People agreed with the former Senator that Johnson and other Republicans in Congress need to meet the moment's urgency.

Johnson himself appeared on MSNBC shortly after Morning Joe 's broadcast ended. He was asked what other "grifting" investigations he'd conducted in Senate—since so-called corruption was obviously such a concern.

That appearance only solidified McCaskill's characterization of him.

Nothing to see here.