Rep. Jacky Rosen Jacklyn (Jacky) Sheryl RosenHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections Google, Apple, eBay to meet virtually with lawmakers for tech group's annual fly-in Senate Democrats demand answers on migrant child trafficking during pandemic MORE’s (D-Nev.) Senate campaign is out with its first negative ad of the cycle, hitting Sen. Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE (R-Nev.) for backing the GOP’s ObamaCare repeal efforts last year.

The 60-second TV ad, which was shared first with The Hill, criticizes Heller for initially saying he wouldn’t support an ObamaCare repeal. It features a clip from his 2017 press conference with Nevada Gov. Brian Sandoval (R), when he said he couldn’t support that legislation.

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The Senate ultimately rejected the measure.

Heller has defended his vote for a “skinny” repeal bill since it would not have touched Nevada’s expansion of Medicaid.

Heller is the only GOP senator up for reelection this cycle in a state that Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE won in 2016.

Friday's ad will also run on digital, in addition to appearing on a new microsite released by the campaign. Rosen's campaign has aired six other TV ads since April — all positive spots about the Nevada Democrat.

“Nevadans deserve a senator with the backbone to fight for their health care, not a spineless partisan politician who bends with the political winds and only looks out for himself,” said Rosen campaign manager Danny Kazin. “Sen. Heller has lost his way in Washington, he can’t be trusted to keep his promises or stand by his convictions, and Nevadans are going to hold him accountable.”

Heller's campaign defended the senator for keeping his promise on pushing for legislation that would protect Medicaid, calling ObamaCare an "abysmal failure."

"Dean Heller has fought to ensure that Nevadans have more choice and control over their health care and he wants to improve the health care system to make it more accessible and affordable for all Nevadans," Heller spokesman Keith Schipper said in a statement.

Heller and Rosen are locked in one of the most competitive Senate races of the cycle, which could determine which party controls the upper chamber next year.

Democrats are largely playing defense in the Senate, with 10 incumbents up for reelection in states that Trump won in 2016. The party has a few opportunities to flip a seat, with Nevada seen as Democrats' best chance to take back a seat.

Rosen again outpaced Heller in second-quarter fundraising. She raised more than $3.5 million, compared to Heller's $2.38 million. But he still has a cash advantage of $2 million.

Heller’s campaign released its own digital ad earlier this week that targets Rosen over her software consulting business. The ad comes after the Reno Gazette Journal reviewed public records and didn’t find a state or local business license for Rosen’s company, which was unnamed and only employed her between 1993 and 2002.

“This attack ad is an attempt by Jacky Rosen to distract from the devastating week she has had," Schipper said. "The revelation that Rosen made up a business and lied about her college degree has blown up across Nevada and Rosen still won’t say anything about the business she supposedly ‘built.'"

Updated at 3:05 p.m.