Republican presidential candidate and former US Senator Rick Santorum is flanked by his daughter Elizabeth (L) and wife Karen (R), as he formally declares his candidacy for the 2016 Republican presidential nomination during an event in Cabot, Pennsylvania, May 27, 2015.[Photo/Agencies]

WASHINGTON -- Former US senator Rick Santorum said Wednesday that he is running for the 2016 presidential race.

I will stand for the principle that every life matters," Santorum, a Republican, said during a running announcement gathering in his hometown, Cabot, Pennsylvania. He promised to create jobs for American families.

Santorum also vowed to defeat the ISIS. He said that the Obama- Clinton team do not understand "peace comes from strength". "We will defeat them (ISIS)," he said.

"Today, I announce my candidacy for President of the United States," Santorum tweeted Wednesday on his Twitter account.

"Rick Santorum is the conservative choice to take on and defeat the Clinton Machine," wrote on his official website.

Santorum, 57, was a senator from Pennsylvania between 1995 to 2007. The move marks a second bid in the presidential race for the Christian conservative, who won a reputation as a strong social conservative in Congress, where he opposed same-sex marriage and the teaching of evolution in schools.

Santorum is the seventh Republican to formally declare a presidential bid. Analysts believes that he will face competition for Christian conservative voters from former Arkansas Governor Mike Huckabee and others. Some believed that he could even be excluded from the early Republican debates, which will begin in August.

He ultimately won 11 states in the Republican's 2012 primary election after an unexpected and narrow victory in the opening contest in Iowa, where he emerged as a conservative favorite after touring the state's 99 counties in a pickup truck.

This time Santorum faces considerable competition for his party's social conservatives in particular. The list of Republicans already courting religious voters includes former Arkansas Gov. Mike Huckabee, a Baptist pastor who won the Iowa caucuses in 2008, former Texas Gov. Rick Perry, Louisiana Gov. Bobby Jindal and Texas Sen. Ted Cruz. And like Santorum, former Florida Gov. Jeb Bush is a Catholic.

Polling suggests a shift in voter attitudes about the importance of social issues, particularly gay marriage, which has long been a defining issue for Santorum.