A judge in the US state of Illinois on Wednesday ordered former President Donald Trump stricken off the state's primary ballot over his role in the January 6 Capitol riot.

The decision by Cook County Circuit Judge Tracie Porter comes as similar anti-Trump ballot measures have cropped up in several states, including a Colorado ruling now before the US Supreme Court.

The question before the nine US justices is whether Trump, the presumed Republican presidential candidate, is ineligible to appear on the Republican presidential primary ballot in Colorado because he engaged in an insurrection -- the 6 January 2021 assault on the US 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 5 March -- also known as "Super Tuesday" -- and the Supreme Court is expected to issue its ruling before then.