“It’s going to be very intense. It’s all hands on deck for grassroots folks and everybody in D.C.,” said Meagan Hatcher-Mays, director at the grassroots organization Indivisible.

After months of slow-moving conversations about impeachment, even some groups who had been pushing for months to impeach Trump “got really caught off guard” when Pelosi finally backed an inquiry, one operative said — and they were immediately outgunned after news broke that their party would try to impeach the president.

Trump’s presidential campaign had already filmed an ad focused on impeachment, which it used to raise more than $8 million in two days after the impeachment push began. Soon after, Trump and the RNC launched a $10 million advertising offensive, some of it targeting House Democrats who are facing difficult reelection bids.

In total, Republicans have spent $6.3 million on impeachment-focused advertising on television, Google and Facebook since Pelosi announced an inquiry on Sept. 24, while Democrats have spent $2.4 million, according to Advertising Analytics.

In the days since, more than two dozen major progressive organizations started joining a daily conference call, hosted by MoveOn, to share plans and strategize. Pelosi’s office has also circulated talking points to organizers off Capitol Hill, urging them to push the most basic facts surrounding Trump’s interactions with Ukraine: That the president asked Ukrainian President Volodymyr Zelensky to investigate Joe Biden, tried to cover it up and put national security at risk.

On the Wednesday call, veteran Democratic pollster Jeremy Rosner and Petkanas zeroed in on the findings of a new poll as they worked to get dozens of Democratic organizations prepared to explain why impeachment is necessary. Voters indicated they found Trump’s interactions with Ukraine most troubling because he “thinks he is above the law,” the survey showed — an argument that will also work as pushback when the White House tries to dodge congressional subpoenas.

But few voters were deeply stirred by the notion that Trump had violated campaign finance laws, the poll showed, making that a likely no-go in the multimillion dollar ad wars to come.

Democratic organizations are beginning to launch ad campaigns to counter Trump’s lead and make the case to voters that he should be impeached. Need to Impeach has already begun spending $3.1 million targeting Senate Republicans on impeachment. The ads no longer feature the group’s former leader, Tom Steyer, who is now running for president, and instead target individual senators: “Tell Susan Collins to put country over party,” one ad airing in Maine says.

The progressive digital organization ACRONYM this week launched a $1 million online campaign focused on impeachment in five swing states, and Indivisible and MoveOn are among the other organizations also considering running media campaigns. Need to Impeach plans to air more ads and ACRONYM is considering expanding its advertising to a national scale.

Trump’s advertising is “largely focused on keeping his base fired up and on fundraising,” said Shannon Kowalczyk, chief marketing officer at ACRONYM. “He’s not spending as much time talking to that broader swath of American people who may have questions about this process and may have not made up their minds.”

Several of the groups with grassroots members feel Democrats will have the votes they need to impeach Trump in the House, so they are already looking to pressure Republican senators to break ranks with their party and vote to remove Trump from office.

Indivisible, which has 5,000 local chapters, has outlined plans to target 13 Republican senators, including several vulnerable lawmakers up for reelection, such as Sens. Cory Gardner of Colorado and Thom Tillis of North Carolina, as well as retiring Sens. Johnny Isakson of Georgia and Pat Roberts of Kansas, and select others who have been critical of Trump, such as Sen. Mitt Romney ofUtah.

In addition to tapping organizers in those senators' states, Indivisible and other groups have begun using phone banking and peer-to-peer texting to allow out-of-state volunteers to rally support across state lines. Some of that work started during the congressional recess, though leaders from grassroots organizations said they are preparing members for a lengthy, intense issue campaign.

Democratic operatives argue the Ukraine controversy has black-and-white contours that play in their favor in ways other recent Capitol Hill battles — such as those over the Mueller investigation and Brett Kavanaugh’s Supreme Court confirmation — did not. With former special counsel Robert Mueller's probe, in particular, those operatives said the lack of a clearly stated conclusion about whether the president had committed impeachable offenses made it difficult to make a public case for impeachment.

Trump’s communications with Ukraine will be easier to sell to the public, Democrats hope: Already, support for impeachment has shot up in recent days, reaching 50 percent in a poll conducted this week by POLITICO and Morning Consult. Even the way the story quickly broke into the public consciousness, after the White House’s efforts to keep it quiet, made for a dramatic unveil with Nixonian echoes, Democrats say.

“We need to keep this as simple as possible,” said David Sievers, campaign director at MoveOn. “It’s worse than Watergate. As much as activists can, [they need to] keep it simple and say, ‘Are we OK with that? If not, there’s only one thing Congress can do in response to that: impeachment.’”