WASHINGTON ―In a new campaign ad Sen. Joe Manchin (D-W.Va.) literally shoots a document representing the Republican-led lawsuit that could end a key and very popular Affordable Care Act provision.

The 30-second spot starts with Manchin mentioning an ad that helped catapult him to the Senate in 2010, in which he took “dead aim” at a complicated cap-and-trade environmental bill that had passed in the House. Manchin, rated by analysts as among the most vulnerable senators on the ballot this year, in the new ad takes aim against the effort to invalidate Obamacare’s insurance protections for people with pre-existing medical conditions.

West Virginia Attorney General Patrick Morrissey, Manchin’s GOP challenger in November’s election, is among the plaintiffs in the lawsuit that would allow insurance companies to deny coverage to people with various pre-existing conditions.

“He is just dead wrong and that ain’t going to happen,” Manchin says in his ad.

Patrick Morrisey's lawsuit would take away health care from people with pre-existing conditions. That's just dead wrong, and that ain't gonna happen. pic.twitter.com/QFTSZGnmdK — Joe Manchin (@JoeManchinWV) September 10, 2018

In a state where polls show approval of President Donald Trump is among the highest in the country, Manchin is making health care the central focus of his re-election bid. And it’s not hard to see why: West Virginia has the highest share of adults with pre-existing conditions of any state.

The Obamacare protections are “the difference between life and death for the 800,000 West Virginians with a pre-existing condition. I will continue doing everything in my power to protect their access to affordable health care,” Manchin said at a health care forum in Huntington, West Virginia,

Last week, attorneys representing 20 Republican state officials walked into a Texas courtroom and ask a federal judge to invalidate all or parts of Obamacare. District Judge Reed O’Connor appeared sympathetic to their case in oral arguments, but he did not immediately rule on the lawsuit’s motion for an injunction against the law. If it succeeds, experts say it will unleash chaos on the health insurance markets and, eventually, leave an estimated 17 million Americans without coverage.

Manchin is a former West Virginia governor whose folksy style and centrist voting record has sustained his career in his state. Indeed, his campaign’s focus on the pre-existing conditions issue stands in sharp contrast to the careful way he has approached Trump’s nomination of Brett Kavanaugh to the Supreme Court.

During last week’s confirmation hearings on Capitol Hill, several of Manchin’s fellow Senate Democrats argued that Kavanaugh’s past writings as an appellate court judge indicate he would take an ax to Obamacare if given the chance as a Supreme Court justice. But Kavanaugh has also faced criticism from some conservatives who say he is insufficiently opposed to the law.

Manchin has not yet said how he will vote on Kavanaugh’s nomination. He supported Trump’s first Supreme Court nominee, Neil Gorsuch, and Republicans are looking to win him over once more.

After sitting in on some of the Kavanaugh hearings last week, the senator told CNN that the judge had “handled himself very professionally.”