The Koch Network is launching a television and radio advertising campaign to push back against President Donald Trump’s tariffs.

According to a press release, the Freedom Partners Chamber of Commerce is heading the six-figure effort, which will target residents of Washington, D.C. and conservative talk radio. According to a transcript of the radio ad, the campaign will focus on recent economic growth. “To keep growing, we must keep trading. Tariffs are not the answer,” the 30-second radio advertisement says. 60-second TV advertisements will air in the D.C. area on June 25, and the radio message will begin broadcasting nationally on the same day.

Joining the effort are a number of other Koch Network groups, such as Americans for Prosperity and the LIBRE Initiative, who will send letters on Wednesday to every member of Congress encouraging support for a trade bill sponsored by Utah Republican Mike Lee in the Senate, alongside Ohio Republican Warren Davidson in the House.

The bill, known as the Global Trade Accountability Act, would reclaim some of Congress’s Article 1 powers over trade that have eroded over the decades by requiring congressional approval for trade actions, such as withdrawing from treaties or imposing new tariffs. Lee introduced it on the day of Trump’s inauguration, January 20, 2017. The legislation has mostly stalled in the Senate, where it has five cosponsors. Davidson introduced the companion bill in the House this spring after Republicans were blindsided by Trump’s far-reaching steel and aluminum tariffs, which were imposed on national security grounds.

Republicans have widely criticized Trump’s use of unilateral trade authorities, particularly Section 232 of the Trade Expansion Act, to impose tariffs under national security pretenses, but few have been willing to pass legislation to prevent it. Tennessee Republican Bob Corker launched a bipartisan effort to limit Trump’s use of Section 232 after the White House announced Trump’s intention to use Section 232 in order to impose 25 percent tariffs on automobile imports under the same national security claims, but Republican leaders in both chambers have been skeptical of the idea.

In a recent interview, Lee told THE WEEKLY STANDARD that garnering support for his bill has presented a challenge because his colleagues are used to delegating congressional authorities to the executive branch. “It takes some time to get people thinking about the fact that it wasn’t always that way and that constitutionally, it’s not supposed to be that way,” Lee said.

Freedom Partners hopes to win more support for Lee’s bill by touching on the Republican party’s midterm message of economic growth and warning against the potential harms that protectionism can bring for American consumers and industries.

“American trade is a priority for our network because it raises people out of poverty and improves lives,” Freedom Partners Executive Vice President James Davis said in a statement. “These ads are an important part of our overall campaign, which also includes significant plans for grassroots mobilization and public education. We want to build and support a coalition of American trade champions to advance more open exchange between nations and to remove trade barriers that make us poorer as a whole.”