The Republican party has taken “a wrong turn” under Donald Trump, according to three GOP challengers to the president, and is heading down the road to totalitarianism as states cancel primaries in an attempt to give Trump an unimpeded path to the nomination in 2020.

In a joint opinion column for the Washington Post, Mark Sanford, Joe Walsh and Bill Weld noted that “the Democratic primary challengers are still engaged in a heated competition of debates, caucuses and primaries to give their voters in every corner of our country a chance to select the best nominee”.

They asked: “Do Republicans really want to be the party with a nominating process that more resembles Russia or China than our American tradition?”

Sanford, a former South Carolina congressman and governor, and Walsh, a Tea Party congressman from Illinois turned talk radio host, recently joined Weld, a former governor of Massachusetts, in seeking to offer a Republican alternative to Trump.

Pending any legal challenges, they will not be able to do so in Arizona, Nevada, Kansas and South Carolina, which have cancelled their nominating contests.

“A president always defines his or her party,” the three men wrote, “and today the Republican party has taken a wrong turn, led by a serial self-promoter who has abandoned the bedrock principles of the GOP.

“In the Trump era, personal responsibility, fiscal sanity and rule of law have been overtaken by a preference for alienating our allies while embracing terrorists and dictators, attacking the free press and pitting everyday Americans against one another.

“No surprise, then, that the latest disgrace, courtesy of Team Trump, is an effort to eliminate any threats to the president’s political power in 2020.”

Republican presidents have been damaged by primary challenges before. In 1992, the paleo-conservative Pat Buchanan ran against George HW Bush before the president lost the White House to Bill Clinton. But no sitting president has been denied his party’s nomination since Chester A Arthur in 1884.

The current challengers do not stand much chance of upsetting or even minorly damaging Trump. He has treated them with his usual disdain, exaggerating his (admittedly very high) popularity among Republicans, coining a customary nickname – “The Three Stooges” – and homing in on his challengers’ weaknesses.

While governor of South Carolina, Sanford said he was absent from the state because he was hiking the Appalachian trail. In fact he was in Argentina, conducting an extra-marital affair.

Walsh, who won office in the Tea Party wave of 2010 but lost it in 2012, has apologised for voicing racist opinions about Barack Obama.

Weld, a relatively liberal Republican, was governor of Massachusetts between 1991 and 1997, has never held national office and was running mate to the Libertarian candidate, Gary Johnson, in 2016, winning a little more than 3% of the popular vote.

Nonetheless, the three men press on.

In March, Weld told the Guardian: “Don’t forget, George HW Bush’s numbers were at 91% in December 1991, and look what happened to him.”

For the Post, he, Walsh and Sanford wrote: “Under this president, the meaning of truth has been challenged as never before. Under this president, the federal deficit has topped the $1tn mark.

“Do we as Republicans accept all this as inevitable? Are we to leave it to the Democrats to make the case for principles and values that, a few years ago, every Republican would have agreed formed the foundations of our party?”