Former Premier Silvio Berlusconi says he has reached a deal with the Northern League, his onetime coalition partners, to jointly run in elections next month.

Berlusconi announced the late-night deal signed at his villa near Milan on Italian radio on Monday. But the billionaire media mogul said it was still unclear whom the center-right coalition would back to run as premier.

Berlusconi has for weeks been toying with a run for a fourth term. He has already come out strongly against Premier Mario Monti's unpopular decision to impose a property tax on first homes.

While the Northern League has ruled in coalition with Berlusconi three times, the relationship has been rocky at best — with the League being behind the downfall of previous Berlusconi governments.