One thing became clear after the first Republican presidential debates: performance matters. 

Carly Fiorina rose in the polls after her stand-out evening in the undercard debate. Ben Carson, who scored some memorable lines, is now in solid second place. Other candidates seen as putting up a mild performance that night -- notably Jeb Bush and Scott Walker -- have steadily slipped. 

So ahead of round two on Sept. 16, the campaigns are nailing down tactics they hope will help them break out of the pack -- or at least prevent them from fading. 

New Jersey Gov. Chris Christie, still trailing in the polls, vowed he would not simply stand by if it seems the moderators are overlooking him. 

"We may be changing tactics if I get to like 15 questions in a row. ... You're gonna go: 'Uh oh, he's gonna go nuclear now,'" Christie quipped on "The Tonight Show" earlier this month. 

Several other candidates are becoming more outspoken in the run-up as well. 

Bush, who attempted to avoid slip-ups and clashes with other candidates on Aug. 6 following a few pre-debate stumbles, now regularly calls out front-runner Donald Trump on the campaign trail. 

Speaking about his appearance on "The Late Show with Stephen Colbert" earlier this week, where the host tried to prep him for a "Trumpier" debate, the former Florida governor said: "If the debate was going to be that simple ... then I wouldn't need to prepare." 

CNN announced Wednesday that 11 candidates have qualified for the Sept. 16 main debate stage, based on recent polling. That includes Fiorina -- after the network adjusted their debate criteria to account for more recent surveys. 

She will share the stage with Trump, Christie, Bush, Wisconsin Gov. Walker, Texas Sen. Ted Cruz, Kentucky Sen. Rand Paul, Florida Sen. Marco Rubio, retired neurosurgeon Carson, former Arkansas Gov. Mike Huckabee and Ohio Gov. John Kasich. 

Walker, who has been ramping up his rhetoric in recent weeks, announced in a speech Thursday plans to "wreak havoc" on the status quo in Washington if he becomes president. If he sticks to that message in the Sept. 16 debate, it would mark a departure from tactics he used in the first debate where he largely focused on Hillary Clinton. 

The Walker camp also unveiled intentions to challenge his GOP rivals on health care policy at the upcoming debate. A Walker aide said the candidate "will start to contrast plans with fellow Republicans on the stage," as well as continue contrasting himself with the Democratic front-runner. 

Fiorina is perhaps the candidate who stands to gain the most, having jumped to the main stage for the upcoming event. 

Fiorina gained prominence after the "happy hour" debate on Aug. 6 by relentlessly attacking Trump and Clinton. Now, on a bigger stage with more candidates and opportunity for Trump to fire back, she may have to amend her strategy. 

The Fiorina campaign did not reveal any specific debate tactics, but Press Secretary Anna Epstein said, "Carly is looking forward to introducing herself to more voters and continuing to make the case as a true conservative ready to challenge the status quo." 

Carson, who has a comfortable position in the polls and is second only to Trump, said he just plans to be himself. 

"I am not interested in sounding like a politician. Instead, I want to continue the debate about the issues we all face," said Carson in a Facebook Q&A on Aug. 30. "I want to be me for as many minutes as they will give me." 

Kasich plans to stick to the strategy he has had all along.    

"Just like the past debate, the governor is focused on telling his story and positive vision for the country," Kasich spokesman Chris Schrimpf said. 

Fox News' Jessica O'Hara contributed to this report.