Immigration reform has been one of President Obama’s biggest political battles, and that looks to be no different for the growing pool of candidates for the 2016 presidential race. As the field fills out, most recently with Hillary Clinton and Florida Sen. Marco Rubio entering the race, questions remain over whether the next White House occupant might help or hinder prospects for comprehensive reform, or try to undo Obama’s immigration executive action for undocumented immigrants.

Marco Rubio

Republican candidates still face the tricky balancing act of attracting Latino voters while appealing to party hardliners on immigration. Rubio, one of the two Latino candidates in the ring so far, is already facing scrutiny regarding his 180-degree turn on immigration in recent years. Rubio one of the original sponsors of the “Gang of Eight” bipartisan immigration bill in 2013 that was considered Congress’ best chance at the time for passing comprehensive reform. While that bill assured a range of border security requirements be met — including completing 700 miles of border fencing and increasing the number of Border Patrol agents — it also provided a pathway to citizenship for Dreamers (undocumented immigrants who arrived in the U.S. as children), streamlined legal immigration systems and even included a program to reunite deported parents with their families in the U.S. under certain conditions.

But since that bill faltered in Congress, Rubio has changed tack on immigration, throwing his support behind piecemeal legislation and emphasizing border security over talk of any kind of relief for undocumented immigrants. “The only path forward that has any chance of success is to bring illegal immigration under control [first],” Rubio told reporters in January. After that, he said, lawmakers could then streamline the legal immigration process.

In the past, he’s supported in-state tuition for Dreamers and planned a bill that would grant temporary deportation relief to those immigrants under certain conditions. But he criticized Obama’s Deferred Action for Childhood Arrivals (DACA) program, announced in 2012, saying it had “poisoned the well” for immigration reform. Last summer he also called for “winding down” the program, saying it was fueling the surge of unaccompanied Central American migrants at the southwestern border.

Ted Cruz

Texas Sen. Ted Cruz, the other Cuban-American presidential contender in the field, has long been a vocal opponent of Obama’s immigration policies and any relief for undocumented immigrants. He voted against the 2013 comprehensive reform bill, criticizing its provisions as providing “amnesty” for illegal immigration, and advocated defunding both DACA and Obama’s more recent executive action for undocumented parents of U.S. citizens, known as DAPA (Deferred Action for Parents of U.S. Citizens and Long-Term Residents).

Instead, Cruz has pushed for dramatic increases in border security, including tripling the number of Border Patrol agents, quadrupling the amount of border monitoring and surveillance equipment, and building a double-layered fence along the U.S.-Mexico border.

Hillary Clinton

Clinton, the presumed Democratic nominee, has remained relatively reticent on immigration issues since taking some heat during the 2008 primary for reversing her stance on drivers’ licenses for undocumented immigrants. (She appeared to support such a policy at first, but later denied she was advocating for such a move.) In recent years, she’s expressed support for Obama’s executive action as well as a bipartisan comprehensive bill that includes a pathway to citizenship for immigrants living illegally in the U.S. At the same time, she has faced pressure from immigration activists to advocate more for reform.

Last summer she spoke out on the surge of Central American migrants at the southern border, saying the U.S. would send back those who crossed into the U.S. illegally. “We have to send a clear message: Just because your child gets across the border doesn’t mean your child gets to stay,” she said during a town hall meeting in June. “We don’t want to send a message that is contrary to our laws or encourage more children to make that dangerous journey.”

Clinton has defended Obama against criticism of his deportation record as more than 2 million immigrants have been deported during his time in office. At the June town hall meeting, she reminded the audience there were “laws that impose certain obligations on him” on deportations. One of those laws, however, was passed while she was in the White House as first lady: The Immigration Reform and Immigrant Responsibility Act, signed by Bill Clinton in 1996, initiated the practice of expedited removal, in which immigrants are deported from ports of entry without access to an immigration hearing.

The law also expanded the list of crimes that could result in deportations for green-card holders and immigrants living in the U.S. illegally, putting acts like murder, rape, forgery, perjury and tax evasion under the label of “aggravated felony.”  

Rand Paul

Kentucky Sen. Rand Paul, meanwhile, has labeled himself a “moderate” on immigration policy, and said he supports providing work authorization for the 11 million undocumented immigrants already in the United States. “I am in favor of doing immigration reform, but it should be done in the right fashion,” he said in January.

However, he also voted against the bipartisan Senate bill, saying it failed to address border security adequately, and submitted a proposal to overturn Obama’s most recent executive action. Four years ago, he also raised eyebrows when he backed a constitutional amendment to end birthright citizenship for children of undocumented immigrants.

Jeb Bush

Former Florida Gov. Jeb Bush hasn’t officially declared his candidacy for the presidency, but he said he is “actively exploring” a run and is widely expected to join the field of contenders. Last week he expressed a softer tone on immigration than some of the other Republicans presidential hopefuls, saying many immigrants who came to the U.S. illegally “crossed the border because they had no other means to work to be able to provide for their family.”

“Yes, they broke the law, but it’s not a felony. It’s an act of love,” he said, according to the Washington Post.

Bush has criticized Obama’s executive action on immigration although he said he supports a pathway to citizenship for Dreamers. But on recent occasions when asked if he would rescind the executive action as president, Bush has declined to answer the question, reiterating immigration reform must be done through Congress rather than through the president.