Sen. Joni Ernst of Iowa is the latest Republican to lend a hand to Sen. Jeff Flake's re-election fundraising efforts.

Ernst is a rising GOP star nationally who last year was reportedly under consideration to be President Donald Trump's running mate. She also has been mentioned as a possible future Republican presidential candidate.

Ernst, who was elected to the U.S. Senate in 2014, is set to appear with Flake, R-Ariz., in Phoenix at a Sept. 7 Young Republican meet-and-greet event and at a Sept. 8 "Women for Flake" fundraiser, the campaign said.

Previously, former President George W. Bush and 2012 Republican presidential nominee Mitt Romney headlined events to raise money for Flake, who is facing potentially tough primary and general-election battles in 2018 as well as attacks from Trump, who most recently blasted him as "weak" on border security and crime.

Two recent polls have shown Flake trailing a primary challenger, former state Sen. Kelli Ward of Lake Havasu City.

Last year, Ernst was among a group of conservative freshman U.S. senators who came to Arizona to help Sen. John McCain, R-Ariz., get through a similarly tough race.

Flake got crosswise with Trump in 2016 when he refused to endorse or vote for Trump, his party's presidential nominee. But the Aug. 1 publication of Flake's book, "Conscience of a Conservative: A Rejection of Destructive Politics and a Return to Principle," reignited the simmering feud.

In the book, Flake takes the GOP to task for embracing Trump-style populism, nationalism, protectionism and conspiracy theories at the expense of traditional conservative values such as free trade.

Senate Republican leaders and Flake's GOP colleagues have largely sided with Flake following the Trump attacks.

TALKING POLITICS: Listen to our Arizona politics podcast, The Gaggle, on Apple Podcasts,SoundCloud, Stitcher or Google Play.

Nowicki is The Arizona Republic's national political reporter. Follow him on Twitter @dannowicki.

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