Billionaire activist Tom Steyer is bringing a nationwide town hall tour promoting President Trump’s impeachment to Oakland, but he’s got more in mind than leading a pep rally for Bay Area liberals. He intends to shame Democrats who aren’t cheering along with him.

“I think there’s a question about what people are willing to say in public that they know is true,” said Steyer, a former San Francisco hedge fund manager who commands attention in left-leaning circles for the tens of millions he’s spent on registering voters and backing Democratic candidates.

Many Democrats aren’t calling to impeach Trump, Steyer said, “because of political posturing before the midterms.”

Steyer’s appearance Wednesday highlights a stark divide among the most liberal Democrats: Is removing Trump from office “the most important issue in America right now,” as Steyer insists, or is it premature to move before they have what Dublin Rep. Eric Swalwell calls “an impenetrable set of facts”?

Some Democrats fear losing the moral and political high ground by backing impeachment before Special Counsel Robert Mueller’s investigation into any Trump campaign ties to Russian election meddling is complete.

It will be impossible to win Republican support for impeachment in the GOP-controlled Congress unless Mueller finds evidence of criminal conduct by Trump himself, Democratic leaders say. Impeachment requires a majority vote in the House, and conviction and removal from office takes a two-thirds vote of the Senate.

“I don’t think it’s helpful for anyone to be pushing impeachment before the investigation is finished,” Rep. Adam Schiff of Burbank, the top Democrat on the House Intelligence Committee, told The Chronicle’s “It’s All Political” podcast earlier this year. While there is a legal standard for impeachment, he said, there “also a political standard. Can you make the case for impeachment in districts around the country?

“That case will be more difficult to make if it looks like this is where we wanted to go all along,” Schiff said.

Last fall, House Democratic leader Nancy Pelosi of San Francisco called Steyer’s impeachment campaign a distraction from the party’s efforts to retake the House. She declined last week to talk about Steyer’s town hall tour.

To Steyer, it’s an outrage that in an area with one of the nation’s highest concentrations of Democratic voters, six House members — Pelosi, Swalwell and Democratic Reps. Jackie Speier, Ro Khanna, Anna Eshoo and Zoe Lofgren — voted against an impeachment resolution in January.

They weren’t alone — only 66 House Democrats supported the resolution. Among them were Bay Area Reps. Barbara Lee, Mark DeSaulnier, Mike Thompson and John Garamendi.

Steyer hoped for better. Nationally, more than 5.1 million people have signed his NeedtoImpeach.com petition since October, and he’s put seven pro-impeachment commercials on national TV.

Now, through his 30-stop national tour, Steyer wants to generate public pressure to get Congress to join him, starting with key Democrats near his home.

He retains a big megaphone in Democratic circles because of the $91 million he spent on left-leaning causes and candidates in the 2016 campaign cycle and the $30 million he pledged to spend on registering 250,000 voters this year.

“Those who condemn Trump but do nothing to back their words with action are enabling the damage he is inflicting,” Steyer said. “Local Bay Area Congress members have repeatedly chosen to ignore their constituents’ voices by voting no on impeachment. The people deserve elected leaders who refuse to back down on our shared principles, and we will ensure their voices are heard.”

Steyer isn’t promising to fund primary challenges to anti-impeachment Democrats. Instead, he envisions his town hall meetings as a “two-way conversation” where he can build public pressure against those who oppose impeachment. He’ll hold his Oakland event at 7:30 p.m. Wednesday at the Impact Hub on Broadway.

Steyer’s target list includes Swalwell, who has shown up regularly on cable talk shows over the past year excoriating Trump for everything from his tax plan to his foreign policy. Swalwell’s House website is filled with charts and videos explaining how “Trump and his team are directly and indirectly tied to Russia.”

But impeachment? Not yet, Swalwell said.

“We shouldn’t run or make this midterm election a referendum on impeachment,” he said. “I think the country wants to be assured that if you were to proceed that way, you would have an impenetrable set of facts to prove that it should happen. And right now we don’t have investigations that allow us to do that.

“I don’t think we should be as reckless with the truth as Trump has been,” he said.

Speier, D-Hillsborough, sides with Swalwell. She has been one of Trump’s most vocal critics in Congress, calling for him to be removed from office under the 25th Amendment, which allows the vice president and two-thirds of the Cabinet to declare a president unfit. She said Trump has shown “erratic behavior and lack of mental capacity.”

But she is not ready to back impeachment yet, either.

“I’m not saying it won’t be appropriate,” Speier said. “But I do not believe that we have the appropriate evidence yet that will make a compelling case. Impeachment is a political act. It’s got to be extraordinarily compelling to get Republicans to support it.”

Steyer counters, “We don’t need any more evidence. The evidence is already there.”

Trump could be impeached for several reasons, Steyer said, including obstruction of justice and violating constitutional bans on profiting from holding his office.

Every day, he said, Trump “does something to make you upchuck.”

Khanna, D-Fremont, said he respects Steyer’s efforts to energize Democratic voters, “but we have different roles. He is a citizen activist and leader. I am a member of Congress who took an oath to the Constitution and (to) follow the legal process that is foundational to our democracy.”

It’s hard to ignore that Steyer’s town hall tour includes three stops in Iowa — the first caucus state on the presidential campaign trail — and other events in swing states Ohio, Virginia, Colorado and North Carolina. But he said the impeachment tour is aimed at registering voters for this year’s elections, not testing his presidential prospects.

“We are really, really, really focused on what’s going on in 2018,” Steyer said. “Anyone who is looking beyond (election day in November) is missing the point.”

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli

Political podcasts

To listen to Joe Garofoli’s “It’s All Political” podcasts with Tom Steyer and Rep. Adam Schiff: www.sfchronicle.com/podcasts

Steyer town hall

Tom Steyer’s public forum on impeaching President Trump ment will run from 7:30 to 9:30 p.m. Wednesday at the Impact Hub, 2323 Broadway, Oakland.