WASHINGTON — The Democratic Congressional Campaign Committee, in a bid to boost the reelection of vulnerable freshman Rep. Sean Casten, D-Ill., will start running a digital ad Monday that could help Republican Jeanne Ives in her primary battle against Evelyn Sanguinetti, the Chicago Sun-Times has learned.

Running that ad suggests that Democrats are betting that Ives will be easier for Casten to beat than Sanguinetti.

The ad, according to the DCCC, is targeting moderate and conservative voters in the 6th District. It’s message, that Ives strongly supports President Donald Trump — damaging in a general election — resonates in a GOP primary.

That the digital buy is not aimed at Democrats is the clue for what the DCCC is really aiming to accomplish.

House Democratic and Republican campaign operations are targeting the suburban 6th District. Casten flipped the seat in 2018, helping Democrats take control of the House.

Ives is a former state representative who narrowly lost a 2018 primary bid against former Gov. Bruce Rauner. Sanguinetti is the former lieutenant governor who was Rauner’s running mate.

It’s the biggest GOP congressional primary in Illinois.

The DCCC ad, to run on Facebook, Instagram and other digital platforms in the 6th District, is headlined, “Jeanne Ives backs Trump 100 percent of the time, noting “Ives is as far-right as they come and stands with President Trump 100 percent” on opposing gun reform, abortion and LGBTQ rights.

Both Ives and Sanguinetti support Trump’s reelection. Rauner tried to keep his distance from Trump during much of his time as governor. Trump remains popular with Republicans.

Kathleen Murphy, an Ives spokesman, told the Sun-Times, that the DCCC is “sorely miscalculating what this race is going to be, then. Nothing we’ve seen indicates that Jeanne would be easier to beat than Evelyn Sanguinetti. That would be a serious miscalculation on their part.”

Sanguinetti told the Sun-Times in an email, “It’s no surprise the Democrats know I am the only candidate that can beat Casten next November and are resorting to primary meddling to ensure he gets the opponent he can defeat.”

The DCCC ad is taking a cue from the Democratic Governors Association playbook. Before the March 2018 Illinois primary, the DGA ran an ad highlighting Ives’ conservative credentials in an attempt to defeat Rauner, who won with 51 percent of the vote.