A Fox News poll has Cruz leading Trump nationally for the first time

A similar lawsuit has been filed against Cruz in Alabama by five voters who are all Trump supporters

Donald Trump has frequently questioned Cruz's eligibility throughout his campaign

Cruz has stated before that he is an American citizen despite being born in Canada and having a Cuban father because his mother is American

he was born in Canada

Illinois voter Lawrence Joyce filed the suit claiming Cruz should not be on the state primary ballot next month

The question of whether or not Ted Cruz can serve as president of the United States is heading to court.

A judge has agreed to hear a lawsuit filed against the presidential hopeful by Illinois voter Lawrence Joyce.

CNN reports that the case will be heard in Cook County Circuit Court in Chicago on Friday in response to Joyce's claim that Cruz should not appear on the ballot for next month's Illinois primary because he was born in Canada.

Cruz has stated before that he is an American citizen despite being born in Canada and having a Cuban father because his mother is American.

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Possible trouble: A Cook County Circuit Court judge in Chicago, Illinois will hear a lawsuit on Friday filed against Ted Cruz (above on Thursday)

Debate: Cruz's birth certificate issued in Canada which identifies his mother as American

Donald Trump has frequently questioned Cruz's eligibility throughout his campaign, and even wrote on Twitter last week; 'If @TedCruz doesn’t clean up his act, stop cheating, & doing negative ads, I have standing to sue him for not being a natural born citizen.'

Trump has said if Cruz were to become the Republican Party's presidential nominee, Democratic partisans could sue in order to have his candidacy nullified, throwing the GOP into chaos just a few months before the November election.

There is another lawsuit that has been filed against Cruz as well in Alabama, where five voters are also hoping a judge will hear their case and have him removed from that state's primary ballot.

AL.com reports that those five individuals are all Trump supporters.

Joyce, the man who filed in Illinois, supports Ben Carson.

The Illinois case will be heard one day before the South Carolina primary this Saturday, a state where Cruz is running second to Trump in polls with Marco Rubio a close third.

A Fox News poll has Cruz leading Trump nationally for the first time.