Donald Trump was sidelined from the Illinois state primaries after a judge struck off the former U.S. President over his role in the Jan. 6 Capitol attack.

The decision by Cook County Circuit Judge Tracie Porter makes Illinois the third state to take similar anti-Trump ballot measures in Maine and Colorado.

With Colorado's ruling now before the U.S. Supreme Court, the question before the nine justices is whether Trump, the presumed Republican presidential candidate, is ineligible to appear on the Republican presidential primary ballot there because he engaged in an insurrection – the Jan. 6, 2021 assault on the U.S. Capitol by his supporters.

Earlier this month, the high Court signaled it was skeptical of the Colorado ruling.

Trump blasted the Illinois decision as politically motivated and unjust.

"Democrat front groups continue to attempt to interfere in the election and deny President Trump his rightful place on the ballot," Trump's campaign said, vowing to appeal the decision.

Anticipating pushback, the judge in Illinois put her decision on pause until Friday to allow an appeal.

"In the meantime, President Trump remains on the Illinois ballot, is dominating the polls, and will Make America Great Again!" Trump's campaign said.

Colorado and more than a dozen other states are to hold their presidential nominating contests on March 5 – also known as "Super Tuesday" – and the Supreme Court is expected to issue its ruling before then.