The Capitol dome at sunset. (Alex Brandon/Associated Press)

Hours before the Republican health-care plan fizzled last month, White House officials marched to the Capitol and urged party leaders to call for a vote on the House floor. Several of them later groused privately that they wanted a list of who was with President Trump and who was against him.

Although that vote was not to be, an informal tally has lived on in recent weeks, passed around the West Wing and within Trump circles. And now an influential outside group with close ties to the president is acting on it.

Leaders of America First Policies, a pro-Trump nonprofit outfit, told The Washington Post on Sunday that it is starting a $3 million advertising campaign to bolster a dozen House Republicans who publicly backed the health-care proposal that has stalled on Capitol Hill.

In a phone call, the Trump campaign veterans who run the organization described the expenditure as a gesture of appreciation to Trump’s friends in the chamber as well as a way to encourage other House Republicans to get behind the effort to revive health-care legislation.

The $3 million “advocacy campaign” will be split among the 12 Republicans beginning Monday and feature broadcast, digital and social components, the advisers said.

Although the chances of passing a tweaked bill remain unclear, this show of support by the organization is the latest example of Trump’s political network trying to stabilize his agenda and rouse GOP lawmakers, many of whom remain skittish about the president because of his underwhelming standing in polls and lingering questions about his commitment to conservative orthodoxy.

Katie Walsh, Trump’s former deputy chief staff who left the White House in late March, is a senior adviser to America First Policies. The group’s chairman is longtime GOP strategist Nick Ayers, who is a confidant of Vice President Pence. Brad Parscale, who ran digital operations for the Trump campaign, is also a senior adviser. Katrina Pierson, its spokeswoman, also was a Trump campaign aide.

Parscale’s team will be using Twitter to rally Trump voters in coming days with the hashtag “#ROC.” That stands for “Repeal Obamacare Caucus,” a designation they hope will catch on with the grass roots of the GOP’s base as Trump tries again on health care.

The television and Web spots are titled “Repeal Now” and feature a script that praises the House members by name for “taking on Nancy Pelosi,” the House Democratic leader, and “standing with President Trump to repeal Obamacare now.”

Still, the main obstacle facing Trump in Congress isn’t losing rank-and-file House Republicans who already support him — it’s the hard-line Freedom Caucus that has not supported the legislation that House leaders have championed.

America First Policies leaders mostly acknowledged that reality and said several times on the call that they could target critics of the health-care plan at some point. But for the moment, they said they’re trying to show House Republicans that there are benefits to standing with Trump on tricky issues, in particular on health care.

“We’re starting positive, but all options are on the table,” one adviser said.

The House Republicans receiving air support are: Gary Palmer (Ala.), Jeff Duncan (S.C.), David Schweikert (Ariz.), Keith Rothfus (Pa.), Rob Wittman (Va.), Tom Graves (Ga.), Scott R. Tipton (Colo.), Thomas Garrett (Va.), David Joyce (Ohio), Michael R. Turner (Ohio), Martha McSally (Ariz.) and Brian Mast (Fla.).