The final Republican presidential primary debate of 2015 will take place today, Tuesday December 15th in Las Vegas, where nine candidates will have one last chance to sharpen their positions before heading into the Iowa caucuses.

Ted Cruz and Donald Trump

There’s expected to be a showdown between Cruz and Trump in the debate tonight.

Front and center will be Donald J. Trump, flanked by Ben Carson and his newest rival Senator Ted Cruz of Texas. Recent polls show Cruz is claiming the front-runner position in Iowa and consequently replacing Carson as Trump’s biggest threat. According to a Fox News poll taken from December 7th-10th, Cruz is slightly ahead of Trump 28-26 percent. This poll had a margin of error of 4.5% points. Cruz also surpassed Trump in a Des Moines Register/Bloomberg poll with a 10-point lead advantage within the same state. Moreover, according to a Wall Street Journal/NBC News Poll, Cruz has risen from his 10% support among Republican primary voters back in October to an overall 22%, which is only 5% shy from Trump’s current 27%. The shift in numbers is primarily due to the fact that a few weeks ago the soft-spoken retired neurosurgeon candidate, Carson, had to face questions about his experience and policy knowledge and senators Cruz and Marco Rubio of Florida began to experience a climb in their respective campaigns. Though to date, Cruz’s surge remains more dramatic than Rubio’s. Meanwhile  Cruz’s strategy of building support among evangelical Christians, Tea Party supporters, and other conservatives continues to take on full effect and challenge Trump. And although Trump has already taken a few hits against the Texas senator by questioning his temperament and qualifications to be president, Cruz’s gloves have not yet come off. Perhaps they will during this last debate.

On the other hand, Senator Rand Paul of Kentucky is set to join the other eight candidates in the main stage on Tuesday and not the undercard debate stage. In order to qualify for the main stage debate candidates must have an average of 3.5% nationally or more than 4% in Iowa or New Hampshire between October 29th and December 13th. Due to low poll numbers, Paul came close to missing out on the main stage debate, but luckily he was saved at the very last minute when CNN reported that Paul was showing viability in Iowa at 5%.

Governor Chris Christie of New Jersey will also join the prime-time debate this time around, considering that during the last debate held on November 10th at Milwaukee he did not qualify for the main debate and was placed in the undercard debate stage instead. Trump, Cruz, Carson, Rubio, Paul, and Christie will be joined onstage by former Governor Jeb Bush of Florida, Carly Fiorina, and Governor John Kasich of Ohio. Tuesday’s debate will be moderated by Wolf Blitzer with CNN’s Chief Political Correspondent Dana Bash and Salem Radio Network’s talk show host Hugh Hewitt as questioners.