Former US Senator Rick Santorum speaks during the National Rifle Association's annual meeting in Nashville, Tennessee April 10, 2015. [Photo/Agencies]

WASHINGTON - Former US Senator Rick Santorum of Pennsylvania told Fox News on Wednesday he will announce on May 27 whether he will seek the Republican presidential nomination in 2016.

A staunch social conservative, Santorum finished second to eventual Republican nominee Mitt Romney in 2012.

Santorum's website said "a special announcement" would be made in Pittsburgh on the evening of May 27.

If he enters the race, Santorum would join a field that so far includes Senators Rand Paul of Kentucky, Ted Cruz of Texas and Marco Rubio of Florida; former Arkansas Governor Mike Huckabee; former Hewlett-Packard Co chief Carly Fiorina; and retired neurosurgeon Ben Carson.