Obtaining citizenship in Malta would provide another passport for Mr. Thiel, who is one of the largest individual donors for the U.S. midterm elections.
Mark Kelly and Blake Masters fought over familiar ground, including abortion, the border and the 2020 election, as they were pressed to clarify their positions.
The debate, set for 9 p.m. Eastern time, will be the first and likely only one to take place in this closely watched Senate contest. Stay here for updates.