A Republican National Committee member from Nevada has hopped on Donald Trump's birther train, tweeting on Monday that not only is Texas Sen. Ted Cruz ineligible to be president, but so is Florida Sen. Marco Rubio.

"Rubio and Cruz are ineligible," tweeted Diana Orrock, a Nevada Republican National committeewoman who serves on the RNC's Standing Committee on Rules and is a member of the RNC Conservative Steering Committee. She's also running for the Nevada state assembly.

Included in her tweet was a link to an article posted on the conservative website News With Views by activist Devvy Kidd, reported Talking Points Memo.

Kidd argues that Rubio is ineligible because both his parents were born outside the United States and were not naturalized as American citizens until Rubio was four years old, even though Rubio was born in Miami, making him a U.S. citizen.

As for Cruz, while his mother is a U.S. citizen, Kidd says he is ineligible because his father was not also a U.S. citizen when he was born in Calgary, Alberta, Canada.

The Constitution requires a candidate be a natural born citizen, and while it doesn't define the term and the Supreme Court has never directly ruled on the issue as it relates to people running for president, most legal experts contend that Cruz and Rubio are both eligible.

The Congressional Research Service, the agency that conducts research for all members of Congress, published a report in 2008 saying that a natural born citizen is anyone who was born in the U.S. or born abroad to at least one U.S. citizen or parent.

Still, Trump continues to insist that Cruz may not be eligible to run for president, while he has left Rubio out of his crosshairs. On Monday, Trump threatened to sue Cruz over his ineligibility unless he apologizes for alleged lies and false advertisements regarding Trump's positions on abortion and gun rights, according to The Washington Times.

Orrock endorsed Trump in January, telling The Daily Beast, "I like a lot of what Mr. Trump is saying. I'm throwing my support behind him because he appreciates my endorsement."