Arizona Republican Senate candidate Sen. Martha McSally has enlisted former United Nations Ambassador Nikki Haley, one of the Republican Party's rising stars, to help fend off a challenge from Democrat Mark Kelly.

McSally, who was appointed by Gov. Doug Ducey after she lost a different seat to Democratic Sen. Kyrsten Sinema, is now in a tight race against Kelly, the astronaut husband of former Rep. Gabrielle Giffords.

She has attempted to rally voters to her side by arguing that Kelly has problematic business ties to China, a claim that Haley echoed Monday while stumping at an event in Scottsdale.

China is the largest geopolitical threat to the United States, the former diplomat and South Carolina governor said, and Kelly's alleged interactions with firms in the Communist nation should be disqualifying.

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According to The Associated Press, Kelly had co-founded a high-altitude balloon company in Tucson that received funding from Chinese investment firm Tencent Holdings. Though the former NASA astronaut no longer works for the firm, his financial disclosures reportedly show he retains an equity stake.

In addition, while an astronaut, Kelly was involved in a forum for young leaders from both countries. After retiring, he also pitched vitamins for a Chinese company.

"I want to know that we're going to send a senator from Arizona to D.C. that understands China is a national security threat, not someone who wants to hold their hand and figure out how to get them to invest in his company," she said.

Former U.N. Ambassador Nikki Haley, right, speaks at a campaign event with U.S Sen. Martha McSally, R-Ariz., Monday, Oct. 12, 2020, in Scottsdale, Ariz. (AP Photo/Matt York)

Former U.N. Ambassador Nikki Haley, right, speaks at a campaign event with U.S Sen. Martha McSally, R-Ariz., Monday, Oct. 12, 2020, in Scottsdale, Ariz. (AP Photo/Matt York)

Kelly has waved off questions about his ties to China -- including during last week's first and only debate -- calling them "false, negative attacks trying to attack [his] patriotism."

The Democrat has pointed to a memo calling on Republican Senate candidates to blame China for the pandemic and asserted that he's "known China as an adversary my entire adult life."

"It doesn't matter who Sen. McSally gets to repeat her lies, they are still lies, and they won't distract Arizonans from her record of voting over and over again to undermine protections for people with pre-existing conditions," Jacob Peters, a Kelly campaign spokesperson, told AZ Central, referring to a popular portion of the Obamacare law, which Republicans have fought to repeal.

With the closely watched race in a dead heat -- much like the presidential standings in the battleground -- Haley appealed to voters McSally seems to be missing: women.

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McSally urged her supporters to ignore what she said were "fake polls," which have fairly consistently shown her trailing Kelly over the past few weeks.