Democratic allies have upped the ante in their effort to defend President Biden’s legislative agenda, with one outfit supporting House Democrats pledging Thursday to spend an additional $10 million for ads, including immediate spots promoting the new child tax credits for most parents of young children.

The effort by House Majority Forward, the nonprofit arm of House Majority PAC, the Democrats’ biggest outside congressional effort, joins several other recent commitments by Democratic-leaning groups for upbeat promotion of Biden’s agenda.

Building Back Together, a nonprofit group backed by Biden’s advisers, announced last week a separate $10 million ad campaign this summer to sell Biden’s agenda. The League of Conservation Voters and Climate Power also recently went public with a third $10 million campaign promoting Biden’s infrastructure proposal in swing states such as Nevada, Arizona, New Hampshire and Georgia.

“It’s important to have a constant drumbeat so that folks know about the ‘build back better’ agenda,” said House Majority Forward executive director Abby Curran Horrell. “This is a winning issue that is really popular.”

The sudden infusion of millions in advertising underscores the importance Democratic groups place in selling measures that may be popular but whose provenance may not be known by all voters.

The party is heading into midterm elections with Republicans expected to gain House seats due to the addition of new seats in red states and the redistricting of existing seats. The party that holds the presidency typically loses numbers during midterm elections, and there are few Democratic seats to spare. The party holds a nine-seat advantage in the House while the Senate is split 50-50, with Vice President Harris giving the party control.

Starting immediately, Horrell’s group plans to spend hundreds of thousands on digital ads about the child tax credit in 17 districts across the country with vulnerable Democratic incumbents. The Internal Revenue Service will begin distributing checks Thursday, providing up to $3,000 in additional refundable tax credits to eligible parents with children under the age of 18. The payments phase out for parents in higher income brackets.

“Lauren Underwood helped put nearly $3,000 in the pocket of nearly every Illinois family,” runs the voice-over on one of the digital spots, targeting that state’s 14th district in suburban Chicago which Underwood won in 2018.

Republicans have also been involved in trying to shape voter perceptions of the Biden agenda with nearly 16 months to go before the midterm elections.

The American Action Network, the nonprofit arm of the Congressional Leadership Fund, the principal Congressional Republican outside group, recently ran ads in vulnerable Democratic House districts criticizing the party’s plans to raise taxes.

“Our way of life is under attack by Washington liberals, proposing a death tax that targets farmers,” says one spot, which the group ran in the district of Rep. Cindy Axne (D-Iowa).

About $6 million in television and digital ads has already been spent this year, said Calvin Moore, a spokesman for the group.

“Families aren’t just going to look the other way as liberals try to tax and inflate away the value of their hard-earned paychecks,” he said in a statement.

Most of the groups advertising right now, including House Majority Forward, Building Back Together and the American Action Network, operate as social welfare organizations, which allows them to accept donations of any size and shield their donors from public disclosure. The ads do not expressly call for the election or defeat of any candidate.

Compared to a normal election year, the levels of political advertising have so far remained relatively low, though there are multiple signs that the spending will increase dramatically in the coming months. The groups involved all say they are not done announcing their spending plans.

“The air war looks a lot more like a slap fight than an actual battle right now,” said one Democratic strategist who has been tracking the spending and who spoke on the condition of anonymity to discuss private conversations.

The ad tracking firm Ad Analytics, which charts spending on television, radio, Facebook and Google, has identified several other groups which have invested significant money advertising this year.

SEIU, a labor union representing service employees, has spent nearly $5 million this year on ads in key states, pushing for legislation that would directly benefit its members. One of the spots includes quotes from Biden selling his plans, and the voice-over line, “It’s time to invest in care.”

A Republican group, One Nation, which has close ties to Senate Republican leaders, has separately spent nearly $4 million on ads opposing the plans, according to Ad Analytics. The ads focus on a wide variety of issues, including Democratic efforts to change federal election laws and Democratic calls to overrule the filibuster in the U.S. Senate.

One spot praises Sen. Kyrsten Sinema (D-Ariz.) for opposing changes to the Senate filibuster, and another spot criticizes her colleague, Sen. Mark Kelly (D-Ariz.), who is up for reelection in 2022 and has declined to make clear his position on the filibuster.

Building Back Together, which launched with the White House’s blessing, has been working behind the scenes to coordinate the outside group efforts to promote Biden’s agenda. It has already spent about $3.1 million on ads, according to Ad Analytics.

“Our strategy is simple: We’re talking directly to the American people about what they care about — defeating the pandemic, reinvigorating our economy, creating jobs, and lowering costs for middle class families” Danielle Melfi, the executive director of Building Back Together, said in a statement. “That’s what Joe Biden proposed in the ‘Build Back Better’ agenda, it’s what got him elected, and it’s what he’s delivering on as President.”