The 30-second spot , released by Friends of the Earth Action, does not mention Democratic front-runner Hillary Clinton.

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The ad will air in Des Moines, Ia., and Manchester, N.H., media markets beginning Tuesday and will run for a week, the group’s president, Erich Pica, told CNN

“He’s proven a bold and fearless voice for a healthy and just world: Senator Bernie Sanders,” the ad begins, alternating between pictures of Sanders and scenic backdrops.

It touts Sanders’ long-standing opposition to the Keystone XL pipeline, which Clinton now opposes but avoided taking a stance on for several years.

“Bernie Sanders had the courage to stand up against the Keystone Pipeline from day one,” the ad says.

The spot also mentions Sanders’ opposition to free-trade agreements like President Obama’s Trans-Pacific Partnership.

Clinton also opposes the deal, but called it the “gold standard” of free-trade agreements while serving as secretary of State under Obama.

“He introduced the bill to keep fossil fuels in the ground on federal land, and he opposes unjust trade agreements that damage our planet,” the ad says.

“It’s why Friends of the Earth encourages you to support Bernie Sanders for president.”