WASHINGTON — For months, impeachment supporters in Congress have been trying to convince their colleagues that President Donald Trump committed impeachable offenses, all detailed in former special counsel Robert Mueller’s report.

Finally, they’ve been handed a gift: a simpler story they believe they can tell the American public, and one that’s persuaded House Speaker Nancy Pelosi and many of her allies to join them.

On Tuesday, more than a dozen Democrats, including many high-profile leadership allies, announced their support for an inquiry. It was a “seismic shift” on Capitol Hill — as many members put it — that ended with a formal announcement from Pelosi that six House committees would pursue an official impeachment inquiry.

In the end, it had nothing to do with Mueller. Instead, the thing that has pushed so many Democrats over the edge was a series of reports that Trump withheld aid money from Ukraine and pressured its president to investigate former vice president Joe Biden’s family ahead of the 2020 election. (This is something Trump has largely admitted to and insisted the two issues are not linked, arguing the call was “totally appropriate” and that he did nothing wrong.)

For Democrats, the Ukraine saga is less in the weeds than the 448-page Mueller report, and it’s a story that several Democratic members said Tuesday was more blatant and easier to explain to the American public.

“In this case, he's skipping the middleman,” Rep. Mark Pocan, a Wisconsin Democrat, said Tuesday. “He's just coming out and saying, ‘Yeah, I did it, and yeah, my office held up the money, and let me save you any more time and just let's get to it. Let's dance.’”

At every town hall he holds, Pocan said, he asks his constituents who among them have read the full Mueller report. In total, just seven people have told him they have. Pocan said that the Ukraine story, on the other hand, is something Americans can understand by watching just a 30-second clip of Trump saying he did it.