WASHINGTON -- Supporters of Republican presidential candidate Donald Trump have filed a federal lawsuit challenging the eligibility of Texas Sen. Ted Cruz (R) to run for president.

The suit, filed in federal court in Alabama, alleges that Cruz is not a "natural born citizen" of the United States, and should therefore be disqualified from seeking the office of president.

Cruz was born in Canada in 1970 to an American mother.

The plaintiffs, Sebastian Green, Shannon Duncan, Kathryn Spears, Kyle Spears and Jerry Parker, are all residents of Cullman County and supporters of Cruz's opponent, Donald Trump, according to AL.com.

Trump, a billionaire real estate developer, first rose to political prominence in 2008 as the leader of the "birther" movement, which claimed that President Barack Obama was not eligible to serve as president because he was not a natural born citizen.

Ever since Trump entered the presidential race last summer, he has made similar claims about Cruz, even as he told crowds that the Texas senator was "a good guy."

In recent weeks, Trump has ratcheted up his attacks on Cruz's eligibility, calling on Cruz to either "settle his problem [of a Canadian birthplace] or get out of race."

It's time for Ted Cruz to either settle his problem with the FACT that he was born in Canada and was a citizen of Canada, or get out of race — Donald J. Trump (@realDonaldTrump) January 25, 2016

The Trump supporters in the lawsuit argue they have a legally protected right to be presented only with qualified candidates on their ballots, and if Cruz were allowed to be listed on a ballot, it would violate that right.

According to the suit, "'natural born' means native born within the United States or its dominions/territories. Canada is not a territory of the United States." They request that the court "declare that Rafael Edward (Ted) Cruz is ineligible and disqualified to run/seek the Office of President of the United States of America."

Similar suits have been filed in federal court in Texas, Arkansas, and Utah, as well as a case in civil court in Vermont. And the elections boards of at least two states, New Hampshire and Illinois, have already issued decisions ruling Cruz eligible to appear on their state ballots.

There is also a consensus on the question among experts. Most legal scholars believe that Cruz is entirely eligible to run for president, because he was born to an American citizen.

“An individual born to a U.S. citizen parent -- whether in California or Canada or the Canal Zone -- is a U.S. citizen from birth and is fully eligible to serve as President,” Neal Katyal and Paul Clement, who ran the Solicitor General's Office under Barack Obama and George W. Bush, respectively, wrote in 2015 in reference to Cruz.

The Huffington Post reached out to both the Cruz and Trump campaigns for comment on Friday, but both so far have declined to discuss the case.

Relations between the two candidates have deteriorated sharply in recent weeks, after they avoided directly challenging one another for most of the fall. Trump has accused Cruz's campaign of playing "dirty tricks" ahead of the Iowa caucus, while Cruz has targeted Trump in ads and interviews, challenging his conservative bona fides.

A tweet from Donald Trump on Friday may offer some insight into the timing of the lawsuit.

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. — Donald J. Trump (@realDonaldTrump) February 12, 2016

Read the whole lawsuit below.