Former Florida Gov. Jeb Bush’s announcement this month that he would “actively explore” a U.S. presidential campaign has led to a CNN poll released Sunday showing him as the early front-runner for the Republican Party U.S. presidential nomination in 2016. Bush, favored by 23 percent of respondents, had a 10-percentage-point lead over New Jersey Gov. Chris Christie, favored by 13 percent.

Bush picked up 9 percentage points since a CNN poll in November showed him with 14 percent support, which also positioned him in the No. 1 spot for 2016 when 2012 GOP nominee Mitt Romney was not offered as a choice. When he was presented as an option, Romney was first in the November poll, with 20 percent; newly minted Republican and retired neurosurgeon Ben Carson was second, with 10 percent; and Bush was third, with 9 percent.

In the latest poll, respondents were also not given Romney as a choice: They had to volunteer his name when asked who he or she would most likely support for president in 2016.

Bush’s lead in the most recent poll is significant because it’s the first time in two years that a potential 2016 contender had a percentage that was higher than the poll’s margin of error. The survey was conducted Dec. 18-21 among 453 Republicans and 469 Democrats. It had a margin of error of plus or minus 3 percentage points.

Besides Bush and Christie, no other potential 2016 GOP contender reached the double-digit percentage level in the latest poll. Carson was third, with 7 percent support. Former Arkansas Gov. Mike Huckabee and U.S. Sen. Rand Paul, R-Ky., both had 6 percent. U.S. Sen. Marco Rubio, R-Fla., and U.S. Rep. Paul Ryan, R-Wis., both had 5 percent. And U.S. Sen. Ted Cruz, R-Texas, Louisiana Gov. Bobby Jindal, Texas Gov. Rick Perry and Wisconsin Gov. Scott Walker all had 4 percent.

The poll asked respondents about they perceived to be Bush’s weaknesses in a Republican primary, including his moderate position on immigration and his support for the Common Core education standards, and whether they would be more or less likely to support him based on those stances.

The biggest issue Republicans had was Bush once describing illegal immigration as an “act of love” that showed undocumented immigrants were concerned about their families, as reported by the Washington Post. A plurality of 42 percent said they were less likely to support Bush because of that statement and 20 percent said they were more likely to support him due to it, while 38 percent said it wouldn’t make a difference.