The idea that all of this is "not that complicated" and "pretty simple" is Ramaswamy's pitch. He's organized his campaign around the idea of simple truths. As expected, he's already drawn attacks from other candidates on the stage. Pence has already hammered him on his lack of experience.
-Analysis by Monica Potts of FiveThirtyEight

Christie received loud boos from the crowd as moderators introduced the Republican field at the start of the debate. As of August 2023, the former New Jersey governor’s unfavorability rating is nearly 49%, according to the latest polling averages [published by FiveThirtyEight], () while his favorability rating hovers at 23%.

-ABC News’ Nicholas Kerr and Olivia Osteen

On COVID-19, Republicans are not happy with the Biden administration’s response. According to a Ipsos/Reuters survey from August, only 27 percent of Republicans think the administration has done the right amount to promote public health and fight COVID-19, compared to 66 percent of Democrats and 55 percent of independents. Thirty-three percent of Republicans said the administration has done too much, and 30 percent said it has done too little.
-Analysis by FiveThirtyEight

Haley has been struggling to distinguish herself among the presidential field, so it's notable that she came out swinging against not just the men on the stage with her but Republicans in Washington, DC as well, for passing those substantial spending bills during the Covid-19 pandemic.
–Analysis from Jacob Rubashkin, Inside Elections

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