History unfolding in Washington as House Speaker Nancy Pelosi announces the start of a formal impeachment inquiry into President Trump.
"So each of these (House) committees will continue their hearings that ultimately may produce individual articles of impeachment," McLennan explained. "Each committee will vote on their own articles of impeachment and advance them to the floor of the house."
What is an impeachment inquiry? A look at the impeachment process
Speaker Pelosi will then choose the charges that the full House votes on.
But even if Democrats garner the 218 votes in the House to impeach; as it stands now, the Republican majority in the Senate is unlikely to convict President Trump to remove him from office.
Plus, the clock is ticking. The presidential campaign is well underway. The Iowa Caucuses are just a week after the Super Bowl.
"The calendar is very tight," McLennan said. "If you're thinking about the situation of removing a president -- that throws the Republicans into a situation we've never seen before. Because they no longer have their leading candidate."
That's worst case for President Trump. The worst case for Democrats would be a repeat of what happened to Republicans when they impeached President Clinton in 1998. The move backfired on the GOP. Democrats ended up winning control of Congress.
"It is a political gamble but a little bit different in that Bill Clinton was not running for reelection," McLennan said. "Republicans are already talking like this could fire them up even more than they are. But on the other hand, Democrats have been looking for this for a long time. They wanted to fight back against President Trump. So this may fire up both sides."
ABC11 asked Professor McLennan for his best guess on how long this impeachment process could last.
He predicted things could move from articles of impeachment in the House to a trial in the Senate on whether to convict or acquit the president all before the end of the fall.