Vermont Sen. Bernie Sanders is making a big bet that his climate credentials can propel him a victory in the Iowa caucuses and secure him as a front-runner for the Democratic presidential nomination.

On Saturday, Sanders is slated to hold a live-streamed summit on the climate crisis at Des Moines Drake University. The event will feature Rep. Alexandria Ocasio-Cortez (D-N.Y.), author Naomi Klein and U.S. Youth Climate Strike co-founder Isra Hirsi, the 16-year-old daughter of Rep. Ilhan Omar (D-Minn.).

The event marks a new emphasis on climate for Sanderss Iowa campaign, as the 78-year-olds base of 18- to 30-year-old voters looks increasingly up for grabs in a heated competition with fellow progressive Sen. Elizabeth Warren (D-Mass.), ascendant moderate South Bend Mayor Pete Buttigieg and former Vice President Joe Biden.

The margins are razor-thin here, said Bill Neidhardt, Sanderss deputy state director in Iowa. If Bernie Sanders can consolidate the climate vote, if he can expand what the climate vote means and win over more union workers, farmers and rural people, that can make the difference.

The campaign spent $1.3 million on a television ad promoting Sanders $16.3-trillion Green New Deal as a natural fit for a top wind energy- and food-producing state, as Vox first reported.

Sanders is also scheduled to hold at least two rallies with Ocasio-Cortez, who gave him one of his biggest-name endorsements, before moving on to two town halls on green jobs in Iowas deep-red 4th Congressional District, which last year reelected white nationalist Rep. Steve King (R-Iowa).