Can anything set Tuesday's Republican presidential debate — the party's fifth airing this year of the crowd of candidates vying for nomination — apart from previous ones? The answer depends in part on the moderator, who this time is Wolf Blitzer, anchor of CNN's "The Situation Room" and the network's lead political anchor.

Blitzer has moderated three GOP presidential debates in the past. In January 2012, he moderated the debate among Republican presidential candidates Mitt Romney, Newt Gingrich, Rick Santorum and Ron Paul. The website Mic graded his performance as poor, awarding him a D for covering important issues and a C+ for controlling the debate.

Blitzer began his career as a journalist in 1972 with Reuters in Tel Aviv, Israel. He later moved to Washington, D.C., as a correspondent for The Jerusalem Post. He became CNN's military affairs correspondent in 1990 and later covered the Clinton White House. 

As with the other GOP debates this year, Tuesday's is a two-part affair. The undercard candidates will take the stage in Las Vegas at 6 p.m. EST, and the prime-time debate is scheduled for 8:30 p.m. EST. The debate is sponsored by CNN and Salem Media Group.

Candidates for Tuesday's prime-time debate qualify by garnering at least 3.5 percent support nationally or 4 percent support in Iowa or New Hampshire, based on national polling. The nine participants in Tuesday's debate include businessman Donald Trump, retired neurosurgeon Ben Carson, Florida Sen. Marco Rubio, Texas Sen. Ted Cruz, Ohio Gov. John Kasich, New Jersey Gov. Chris Christie, former Florida Gov. Jeb Bush, Kentucky Sen. Rand Paul and former Hewlett-Packard CEO Carly Fiorina.

The 6 p.m. EST undercard will include former Arkansas Gov. Mike Huckabee, former Pennsylvania Sen. Rick Santorum, South Carolina Sen. Lindsey Graham and former New York Gov. George Pataki.

The next GOP debate is scheduled for January in Iowa. The third Democratic debate is scheduled for Saturday in Manchester, New Hampshire, and organized by ABC News and WMUR.