Ramaswamy came out hitting the other candidates, saying he's the only one who hasn't been bought and sold. When it came to his comments on Ukraine, though, Pence and Haley are hitting back. "You have no foreign policy experience and it shows," Haley said. As Jacob said, his quick rise is drawing attacks, especially on his lack of political experience.
-Analysis by Monica Potts of FiveThirtyEight

Haley tried to go after DeSantis as he was answering a question on Ukraine but it didn't generate the same back-and-forth as with Ramaswamy, and the moderators quickly moved on to another matter. Clearly Ramaswamy -- his lack of political experience and rapid rise in the polls -- has gotten under the skin of the other candidates on the stage and they're going out of their way to take him down a peg even if it means forgoing opportunities against the ostensible polling leader.
-Analysis by Jacob Rubashkin, Inside Elections

The discussion has turned to the U.S. relationship with China. Republicans’ opinion of China has been steadily worsening over the last six years, according to polling from YouGov/The Economist. As of their most recent survey, 91.4 percent of Republicans said China is an enemy of the United States, while just 3.7 percent said China is an ally. The last time more Republicans said that China was an ally than said it was an enemy was April 17, 2017.
-Analysis by FiveThirtyEight

Pence and Ramaswamy got into another spat, this time over Ukraine, with the vice president attacking his rival over Ramaswamy's calls to send military resources to the southern border, not Ukraine.

"Anybody that thinks that we can't solve the problems here in the United States and be the leader the free world has a pretty small view of the greatest nation on Earth," Pence said.

"I have a newsflash. The USSR does not exist anymore," Ramaswamy shot back, referring to the Soviet Union.

-ABC News' Tal Axelrod

Recent election cycles have shown how debates can substantially alter a candidate’s trajectory. The debates won’t always do this, of course, and early primary polls remain relatively predictive of who will end up winning a party’s nomination. However, a candidate can earn a real polling bounce from a debate — or fall into a valley.

Primary polls are inherently more volatile than general election polls. In a general election, most voters already lean toward one party, so only a small part of the electorate is likely to shift its views over the course of a campaign. But in a primary, voters in one party may be open to multiple candidates because most contenders will share similar views on a number of issues. As a result, exposure to an unfamiliar candidate could prompt voters to begin considering that contender, while a strong or weak performance by a candidate they do know could make them look elsewhere.

For example, early in the 2012 cycle, Texas Gov. Rick Perry appeared to be now-Sen. Mitt Romney’s most serious opponent for the Republican nomination. But in a September 2011 debate, Perry defended a Texas policy that gave undocumented immigrants access to in-state college tuition. The backlash from the GOP base came swiftly, as Perry fell out of contention in the polls, well before a later debate in which he — oops — forgot the name of the third of three federal agencies that he aimed to dismantle as president. Four years later, former tech executive Carly Fiorina had very little support early in the 2016 Republican race, but in August 2015 she stood out in an “undercard” debate. Her polling numbers improved and she made the main stage in subsequent debates, giving her a platform that eventually led Texas Sen. Ted Cruz to make her his vice presidential pick in a last-ditch attempt to rally support against Trump in the 2016 primary.

-Analysis by Geoffrey Skelley of FiveThirtyEight