ABC's David Muir and Martha Raddatz Will Moderate The Democratic Debate

Bernie Sanders and Hillary Clinton pose on stage ahead of the second Democratic presidential debate, in Des Moines, Iowa, on November 15. The next debate will be Saturday, December 19, in Manchester, New Hampshire, and it is the last one before the Iowa primaries. Jim Young/REUTERS

For the third Democratic presidential debate on ABC on Saturday, World News Tonight anchor David Muir and ABC Chief Global Affairs Correspondent Martha Raddatz have the enviable job of watching Bernie Sanders, Hillary Clinton and Martin O'Malley all more-or-less agree with each other. Since Clinton has announced her opposition to the Trans Pacific Partnership trade agreement and the Keystone XL Pipeline, her differences with her two rivals have been substantially muted.

Heading into the last event before the caucuses start, Clinton looks nearly indestructible, despite Sanders's record 2 million donors. In the last two events, the candidates have mostly avoided going after Clinton, settling for a few ineffectual jabs about her ties to Wall Street—but they've refrained from attacking her over the email controversy or over character in general.

That doesn't mean the email scandal can't still dog her, especially with national security being the issue of the moment and new email news in the form of Defense Secretary Ash Carter's admission that he used a personal email account. Muir's biggest interview with Clinton this year went right to that issue; he opened by asking the candidate how she felt about being labeled untrustworthy, and her apology for using a private email server subsequently made headlines.

Muir first rose to prominence for his reporting on Hurricane Katrina, when he documented the unfolding events inside the New Orleans Superdome. He also reported on the BP oil spill before joining ABC's political team for the 2012 election. In an interview with Mitt Romney, he famously got the wealthy former governor to admit he didn't know how much he paid in taxes (something that would be normal for the average taxpayer, but a little damning for a man bemoaning the corporate tax rate and promising to balance the budget). In 2014, he replaced Diane Sawyer as the anchor of ABC World News.

Raddatz brings debate moderation credentials from the previous campaign. She anchored the (famous) 2012 vice presidential debate, when Joe Biden laughed his way to victory over Paul Ryan and called the future speaker of the House's assessment of the Middle East "a bunch of malarkey."

Raddatz specializes in foreign policy and has reported from the Pentagon, the State Department and the White House, including as a correspondent during the George W. Bush administration. Her reporting on the Middle East has included multiple trips to Pakistan, Iraq and Afghanistan. With polls showing that potential voters are increasingly concerned about the spread of terrorism, national security is likely to dominate the discussion.

That's something neither O'Malley nor Sanders wanted. Both Clinton challengers are stronger on domestic issues.

Regardless, when compared to the infighting taking place in the Republican Party, the Democrats have been a snoozefest on TV. Part of the difference in tone can be explained by arithmetic. There are only three candidates for the nomination, obviating the need to whine about speaking time, yell over moderators and opponents, make a big deal out of negotiating the format and debating by insults. It also has to do with the moderators, however; the last two Democratic debates, hosted by John Dickerson of CBS and CNN's Anderson Cooper, avoided questions designed to provoke back and forth.