VIENNA — Police say they have arrested a man who was suspected of tweeting death threats against Austria’s chancellor and a left-leaning candidate for the country’s presidency.

Police spokesman Johann Baumschlager said Thursday the 27-year old has confessed to the tweets. The man, whom police describe as psychologically unstable, was not named in conformity with Austrian anonymity laws.

Baumschlager spoke a day after extremist death threats prompted authorities to upgrade security for Alexander Van der Bellen, who is facing right-winger Norbert Hofer in Dec. 4 elections.

Chancellor Christian Kern is under permanent high-security protection, and Hofer also has police protection.

Police say the man has been charged with “uttering dangerous threats” and “incitement.” Both crimes carry prison sentences on conviction.