There are two ways to impeach a president and remove him from office. Only one of them has ever worked.
The first way is to let evidence from investigations slowly build a bipartisan consensus for impeachment. That's how Richard Nixon was pushed out of office in 1974. (Nixon resigned before he was formally impeached.)
The second way is for just one party to launch impeachment without bipartisan support and hope the country comes along. That's what Republicans did to Bill Clinton in 1998, and it didn't work. Instead, it backfired, making Clinton more popular.
Tom Steyer, the hedge fund billionaire who may be running for a U.S. Senate seat in California, is trying to invent a third way to impeach President Trump — without any of the advantages of the first two.
Steyer, the Democratic Party's largest donor, seems unconcerned that his party doesn't have a majority in the House of Representatives, where impeachment proceedings must begin.
He's urging Democrats in Congress to make Trump's impeachment their goal right now, and a major focus of their congressional campaign next year. He's demanding that every candidate publicly support impeachment to "make it clear where we all stand for Democrats voting in 2018." And he's putting $20 million into a petition drive that's gathered some 2 million signatures in favor of his view.
Trump "is a threat to the American people," Steyer said last week in an interview with ABC News. "Why aren't people willing to stand up and say that? I don't understand it."
Most Democratic leaders think his strategy is self-defeating — beginning with Rep. Nancy Pelosi, who's in charge of winning back the House.
"I'm not making [impeachment] a priority," Pelosi told me last week. "If you're going to go down the impeachment path, you have to know you can do it not in a partisan way."
"We have an investigation in the Justice Department that is seeking facts," she added. "We don't want it to look political."
Her top goal, she said, is "for our country is to come together to win the next election."
That includes trying to win seats in districts where Trump is relatively popular. Pelosi worries that making impeachment an explicit goal will alienate voters who might otherwise be winnable.
Polls suggest that she's right. Most Democrats support impeaching Trump, but independent voters aren't there yet. A Politico/Morning Consult Poll this month found that 40% of voters believe the House should begin impeachment proceedings, but 49% disagree.
Steyer disdains that thinking as small-minded.
"You're asking us not to tell the truth, not to do what's right, because it doesn't fit into the way political tactics are organized in Washington," he said on ABC. It's not clear whether he's even thinking very hard about winning the House. "Don't we have to … do the right thing, not do a political calculation for what's going to happen 14 months from now?" he asked.
But he's gotten pretty tart about his critics.
"I don't look at this as something between Nancy and me," he told the San Francisco Chronicle last month. "It's something between Nancy and the American people."
Pelosi's not rising to the bait — not for a debate with her party's biggest contributor.
"I don't have any complaints with what Tom Steyer is presenting," she said. "I have great respect for Tom."
If Democrats are wondering whether they need to endorse impeachment to mobilize anti-Trump votes in an off year, last week's election in Virginia provided a pretty clear answer.
Their candidate for governor, a colorless establishment Democrat named Ralph Northam, won a resounding victory with a margin of 9 points in a state Hillary Clinton won by only 5 points last year.
In the Democratic primary campaign, Northam faced pressure from his challenger, progressive candidate Tom Perriello, to endorse Trump's impeachment. He resisted.
"Let the facts play out," he said.
Northam made clear he didn't like Trump. "I believe that our president is a dangerous man," he said, "a narcissistic maniac."
But on impeachment, he essentially followed the Pelosi line: It's too early to go there.
On Tuesday, Democrats turned out for Northam in record numbers. Exit polls showed that many of them came out to register a vote against Trump.
The lesson: Democrats don't need impeachment to win a general election. They already own the anti-Trump franchise.
Signing Steyer's impeachment petition will make anti-Trump voters feel good, and that's about all — with one exception.
If Tom Steyer's campaign will help anyone, it's Tom Steyer. He's trying to build support for himself as a potential candidate in deeply Democratic California, where he's mused openly about running for senator or governor next year. Maybe Californians will now come to think of him not just as another wealthy donor, but as the guy who's hot to impeach Donald Trump.
But if the cost of his new stature is a narrower path to a Democratic majority, that will be a high price for his party to pay.