Former Florida Gov. Jeb Bush said in a TV interview Monday that he no longer supports a path to citizenship in an immigration reform bill, a reversal that puts him to the right of the current bipartisan immigration proposal forming in the Senate.

"If we want to create an immigration policy that's going to work, we can't continue to make illegal immigration an easier path than legal immigration," Bush said on NBC's "Today" show. "I think it's important that there's a natural friction between our immigrant heritage and the rule of law. This is the right place, I think, to be in that sense."

Bush, a Republican, supported immigration reform even when many in his party shifted to a harder line stance in the 2012 primary. As recently as last June, he said in interviews that he thought most of the nation's 11 million illegal immigrants should be put on a gradual path to citizenship if they meet certain conditions.

But in the interview, Bush said that many of the immigrants who were legalized in the last immigration reform effort in 1986 did not apply for citizenship when they became eligible, suggesting it was not a key concern for them. "Half the people in '86 that could have gotten amnesty didn't apply. Many people don't want to be citizens of our country," he said. "They want to come here, they want to work hard, they want to provide for their families. Some of them want to come home; not necessarily all of them want to stay as citizens."

Immigrant rights leaders and many Democrats in Congress say any law that legalizes immigrants without giving them the option of earning their citizenship will create a second-class group of people in the country. Frank Sharry of the America's Voice advocacy group slammed Bush's "flip flop" on the issue in a statement Monday.

The bipartisan Gang of Eight in the Senate, which includes Republican Sen. Marco Rubio of Florida, includes a gradual path to citizenship in their proposal. In their plan, immigrants would not be able to get green cards—which lead to citizenship—until a panel of experts has declared the U.S.-Mexico border to be secure. Some prominent House Republicans have said they will not support a bill that includes citizenship, raising questions about whether the Senate proposal could pass there.

It's unclear whether Bush's change of heart on citizenship will have any effect on reform negotiations.

Bush's book "Immigration Wars," which includes his immigration reform proposal, comes out on Tuesday. According to ABC News, Bush writes in the book that he would make an exception for young illegal immigrants who were brought to the country as children. They could become citizens if they graduate high school or join the military.