The real race to watch in Utah this November is not Mitt Romney's -- it's Mia Love's

(CNN)On the Saturday before Utah's primary, Salt Lake County Mayor Ben McAdams was hustling — knocking on doors and on the hunt for persuadable Republicans to support his congressional bid.

Here in Utah's Fourth District, a boot-shaped district covering the suburbs south of Salt Lake City, the primary election Tuesday was a foregone conclusion. The highly competitive race between this popular Democratic mayor and his opponent, Republican Rep. Mia Love, was set this spring when they each secured their party's nomination. Still, recognizing the steep climb he faces to unseat Love, McAdams dashed from house to house, showing the earnest energy and persistence of a former Mormon missionary.
Laced up in a pair of blue Asics that serve as his "parade shoes," McAdams scanned the driveways to game out which voters were home, sometimes hitting doors that weren't on his list. While walking, he scribbled notes on his campaign literature for voters who were out: "Sorry I missed you," he wrote next to his name, tucking it under their doormat.
    While much of the attention in Utah has been focused on the reemergence of Mitt Romney, who is running for US Senate, the Love-McAdams race is much more consequential to both parties.
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    As Republicans try to maintain control of the House, there are few GOP districts in the country where President Donald Trump could cast as long a shadow as he will here. In 2016, Trump drew just 39% of the vote in Utah's 4th District, to Clinton's 32%, with independent candidate Evan McMullin sweeping up much of the remainder.
    The race between these two charismatic players will be one of the most fascinating midterm contests this fall, not only because Love has been one of the most high-profile Republicans to stand up to Trump on immigration, but because national Democrats see McAdams as one of their best chances to gain a foothold on red turf.
    Salt Lake County covers 85% of the 4th District, giving McAdams a distinct advantage when it comes to local issues. When an undecided Republican City Councilman passes by, the Mayor notes that he is staying on top of much-needed street repairs on a nearby corridor. When a mother leaned out the car window to offer encouragement—"We love you. We'll do anything we can to help," 38-year-old Candice Jorgensen told him — McAdams leaned in to give her son a tip for scout camp: "Try the mulberry juice."
    Though McAdams will be well-funded with strong backing from Democrats nationally, he acknowledges the difficulty of his quest in a state where Republicans outnumber Democrats by more than four to one. Strategists on both sides estimate that McAdams must win a fifth to a quarter of Republican votes to prevail.
    Love's challenge will be to turn out Republicans who are not enamored with the President, particularly in more conservative Utah County. Trump's opportunity to nominate a conservative justice to the Supreme Court could help energize the base in Love's district, and she is also likely to get a lift from Romney, the former Republican presidential nominee who is at the top of the ballot as he runs for Utah's open U.S. Senate seat.

    Trump's long shadow in Utah

    But Trump's crude broadsides and harsh immigration policies have been an affront to Utah's huge population of Mormons, who embrace a doctrine of acceptance and inclusivity toward immigrants.
    In such a staunchly Republican state, on