Sen. Susan Collins formally secured the Republican nomination for Maine's U.S. Senate seat on Tuesday, running unopposed in the state's GOP primary and setting up a general election fight that both parties view as critical to control of the chamber.

The 73-year-old senator, seeking a sixth six-year term, now faces Democratic challenger Graham Platner, a military veteran and oyster farmer backed by progressive heavyweights Bernie Sanders and Elizabeth Warren. Collins told Fox News Digital she expects Maine voters to see Platner as too far left for the state.

The race is one of a handful across the country that will determine whether Republicans keep their slim Senate majority. Democrats need to flip seats to reclaim the chamber, and Chuck Schumer has made Collins a priority target, something the senator herself acknowledged bluntly.

Collins names Schumer's targeting pattern

Collins did not hold back about where the Democratic pressure is coming from. In a recent interview with Fox News Digital, she laid out the dynamic plainly:

"I have been the No. 1 target of Democratic Leader Chuck Schumer, not only in this campaign, but the last two campaigns as well. I'm always his No. 1 target."

That claim carries weight given the 2020 cycle, when Collins trailed then-Democratic challenger Sara Gideon, the Maine House speaker at the time, before winning re-election by nearly nine points. Schumer's operation poured resources into that race and came up empty.

Now Schumer faces a different landscape. His own caucus has shown signs of fracture, with Senate Democrats breaking ranks on major votes and progressive frustration with leadership boiling over publicly.

Collins, for her part, projected confidence, but not complacency.

"I believe that will be the conclusion of Maine voters. But, obviously, I don't take anything for granted."

Platner's progressive backing, and mounting controversies

Platner has positioned himself as a populist outsider, taking aim at corporate influence and calling Collins a symbol of "broken Washington" and "a generation of politicians who have failed us." He dismissed Collins' moderate Republican image as a "charade."

He has drawn support from Sen. Sanders, Sen. Warren, and Rep. Ro Khanna of California. On May 24, Sanders stood alongside Platner at a "Fighting Oligarchy" tour stop at the Collins Center for the Arts on the University of Maine campus in Orono.

That progressive firepower helped Platner push aside the Democratic establishment's preferred candidate. Two-term Gov. Janet Mills, backed by Schumer and the party apparatus, dropped out earlier this spring after significantly trailing Platner in both fundraising and polling.

But Platner's candidacy has been dogged by a series of personal controversies that have forced him onto defense. Last fall, soon after launching his Senate campaign, controversial Reddit posts made headlines. Platner apologized.

Then came questions about a skull and crossbones tattoo. Platner said he got it in 2007 while drinking with fellow Marines stationed in Croatia. He said he covered it up with a new design after learning last year that it resembled a Nazi symbol.

The pressure from progressive allies like Sanders has not insulated Schumer from growing frustration from his own left flank, which complicates the Democratic leadership's ability to manage races like this one from Washington.

Last week, new allegations surfaced from ex-girlfriends describing what Fox News Digital characterized as a history of rape fantasies, heavy drinking, and violent episodes. Platner responded by acknowledging his struggle with post-traumatic stress disorder from four tours of duty in Afghanistan and Iraq:

"I've been open about what was a very dark period of my life where I struggled with undiagnosed PTSD, too often self-medicated with alcohol, and was a far from perfect boyfriend."

He added: "I take responsibility for all of that, and wish I had been better. Any characterization beyond that is false, and I believe, politically motivated."

Platner also said: "I'm not proud of who I was then, but I am proud of the work I've done since, and the movement we are building in Maine."

Collins contrasts records, and runs on constituent service

Collins signaled she intends to make the race a direct comparison between her legislative record and Platner's approach. An outside political group aligned with Collins has already been running ads spotlighting Platner's controversies.

"Obviously, I'm going to be contrasting my record of achievement and accomplishments with Graham Platner's approach."

On the trail, Collins has leaned into bread-and-butter issues. On May 5, she toured a food bank in Harrison, Maine, that expanded thanks to federal funding she helped obtain. She emphasized her work on the low-income heating assistance program, which she said "helps low-income families and seniors stay warm during the cold winter months." Collins added that she recently made sure the final tranche of money was released, citing the high cost of living in the state.

She also stressed her opposition to cuts "in food stamp benefits and in other programs that are designed for low-income families because I know how important they are."

That kind of constituent-service pitch has long been Collins' electoral formula in a state that does not always break Republican. It worked against Gideon six years ago when national Democrats spent heavily and lost.

Meanwhile, Platner held an energy event in Ellsworth, Maine, on May 11, part of his effort to build a working-class populist brand. He has attacked Collins for supporting parts of President Trump's agenda, a line of attack Democrats believe resonates given the president's approval ratings in the state.

Platner put it sharply: "She and Republican politicians like her have prioritized the interests of billionaires and corporations over people."

Questions about whether Schumer himself faces a primary challenge from his party's progressive wing add another layer of uncertainty to the Democratic Senate strategy heading into the midterms.

The stakes for Senate control

Republicans hold a slim Senate majority. Democrats see this cycle's midterms as their best chance to claw it back. Maine is one of the top battlegrounds.

Collins has been here before. Six years ago, she was counted out, trailing in polls, facing a well-funded opponent, absorbing national Democratic spending. She won by nine points.

On Friday, Collins cast her 10,000th consecutive Senate vote, a milestone that drew bipartisan praise. It is the kind of institutional credential that plays well with Maine's older, independent-minded electorate, and the kind of record that a first-time candidate carrying personal baggage will struggle to match.

Collins anticipated the flood of attack ads heading her way and offered a pointed response:

"Fortunately, the people of Maine are smart, and they know lies and distortions when they see it."

Schumer has made Collins his top target before, and his recent partisan messaging battles suggest the intensity will only increase as November approaches.

Democrats chose to bypass their own governor in favor of a progressive insurgent endorsed by Bernie Sanders and Elizabeth Warren. They are betting that a populist outsider can do what a well-funded establishment candidate could not six years ago.

Collins is betting that Maine voters will look at the full picture, her record, his controversies, and who is pulling the strings, and reach the same conclusion they reached last time. Given what the full picture now includes, that may not be much of a bet at all.