Donald Trump repeatedly argued during the 2016 election that the Democratic presidential primaries were “rigged” against Sen. Bernie Sanders.

Four years later, as nomination rivals Sen. Amy Klobuchar and Pete Buttigieg dropped out of the Democratic race and endorsed former Vice President Joe Biden just ahead of Super Tuesday, President Trump repeated his claims that the primaries were “rigged” against Sanders, the populist firebrand lawmaker from Vermont.

But now – in a twist -- the president’s reelection campaign and the Republican National Committee (RNC) are being accused of “rigging” competitive GOP Senate and House primaries in the battleground state of New Hampshire – just days after Trump took sides and endorsed a candidate in each of the races. That spurred the Trump campaign and the RNC to no longer help the candidates the president didn’t endorse.

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The “rigging” charge comes from retired Army Gen. Don Bolduc, the main Republican Senate candidate who didn’t land the president’s endorsement. And Matt Mayberry, a former New Hampshire GOP vice chair who saw his congressional primary rival win the president’s endorsement, stressed in an email to supporters to “Let New Hampshire Voters decide New Hampshire Elections.”

While the president has made more than 200 political endorsements since taking over in the White House in 2017, he hasn’t often weighed in on competitive Republican Senate and House primaries. And what makes his endorsements in New Hampshire even more noteworthy is the political pushback they sparked.

The catalyst for all the commotion was the president’s tweets two weeks ago announcing his endorsements.

“He was a winner in my Administration and he will always put America First,” Trump tweeted as he backed Republican congressional candidate Matt Mowers, a longtime Republican political operative who worked on Trump’s 2016 general election campaign and transition before being appointed by the White House in 2017 to a high-ranking State Department position.

“Matt has my Complete and Total Endorsement! We need him in Washington now!” the president emphasized.

Mowers and Mayberry, a former Dover city councilor who strongly backed Trump during the 2016 general election, are the two main GOP candidates vying to challenge freshman Democratic Rep. Chris Pappas in November in the state’s 1st Congressional District.

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A day later the president announced his support for Messner, an Army Ranger veteran who graduated from West Point and a self-made millionaire trial lawyer.

“Corky Messner (@CorkyForSenate) will be a fantastic Senator for New Hampshire! A West Point graduate, he served our Country in the Army with distinction. Strong on Jobs, Crime, Vets, Military and the Second Amendment......We need Corky in Washington – he has my Complete and Total Endorsement!,” Trump tweeted.

Messner and Bolduc -- a New Hampshire native who was awarded two Purple Hearts and five Bronze Star medals during his more than three decades of service in the Army, including 10 tours of duty in Afghanistan – are the two leading candidates in the GOP Senate primary. The winner of the September Republican primary will face off in November against Democratic two-term incumbent Sen. Jeanne Shaheen, a former governor of the state.

As a result of the endorsements, both Bolduc and Mayberry will no longer receive help from the Trump Victory organization, which is the combined effort of the Trump reelection campaign and the RNC. Messner and Mowers are now enjoying the full support from Trump Victory, which includes access to the RNC’s vast voter lists.

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Trump Victory’s move comes even though neither the chair of the New Hampshire GOP or the state’s two RNC committee members gave their blessing, which is required by Republican Party rules. A Republican source with knowledge of the decision-making on the endorsements told Fox News that because New Hampshire holds its state primary less than two months before the November election, it’s already considered in a sense to be in the general election phase.

Bolduc was steamed by the decision. He charged during a virtual town hall that “I consider this a form of election rigging. Why even have a primary election if Washington, D.C., is going to decide the candidate.”

And the retired brigadier general told Fox News that “Granite Staters do not like to be told who to support and quite frankly I do not like to be told to concede before Granite Staters make their choice. Granite Staters must decide this primary election not Washington, D.C.”

The National Republican Senatorial Committee’s staying neutral, and the New Hampshire GOP isn’t taking sides in the race either, following state party rules that mandate it remains neutral in contested primaries.

“The president can endorse anyone he wants," popular two-term Republican Gov. Chris Sununu told TV station WMUR. "I think the party leadership here in New Hampshire said, ‘Look, we’re going to stay neutral because there’s a primary, and a primary is a good, fair process.’”

The RNC declined to comment on the controversy, but longtime New Hampshire resident and veteran Republican strategist Corey Lewandowski weighed in.

Lewandowski – who managed Trump’s first presidential campaign from its inception in 2015 until June 2016 and who remains a close political adviser to the president -- pushed back against Bolduc’s claims.

“It’s clearly not being rigged,” he emphasized on Monday during a radio appearance on the news-talk program "New Hampshire Today with Jack Heath."

“When you run for the United States Senate and you have $100,000 in the bank against a two-term incumbent U.S. senator who also served three-terms as the governor of New Hampshire, that’s not a serious candidate,” Lewandowski said of Bolduc, who’s struggled with fundraising over the past year.

Messner - who registered to vote in New Hampshire in 2018 after living for years in Colorado - has the ability to self-fund and so far has invested more than $3 million of his own money into his Senate campaign.

Bolduc claims that the president’s endorsement of Messner has benefited his bid, touting that “we have seen an increase in volunteers, an increase in fundraising, an increase in sign requests, and a groundswell of support since the announcement of the president’s endorsement of my opponent.”

In the House primary, Mowers – a former executive director of the New Hampshire GOP – was far outpacing Mayberry in the race for campaign cash even before the president’s endorsement.

But Mayberry, a longtime state Republican activist who served in the Air Force, warned that “what the RNC is proposing – to directly spend resources in support of primary candidates in contested primary races – would be absolutely devastating to Republican efforts to pick up two Congressional seats, a U.S. Senate seat and to carry the state for President Trump in November.”

And Mayberry pointed to president’s historic 2016 campaign to make his own case.

“I am running the same election strategy Donald Trump did in the 2016 presidential primary,” Mayberry told Fox News. “Trump disregarded the Washington establishment, who wanted [Jeb] Bush, and he spoke directly to the citizens of New Hampshire and I am doing the exact same thing. It worked out pretty well for President Trump and I expect the same level of victory in September."