With all the attention the Republican presidential candidates have paid to illegal immigration over the past year, it’s been on the back burner for Democratic co-frontrunners Hillary Clinton and Barack Obama.

A reader recently wrote and asked how Clinton and Obama differ - if at all - on immigration issues and where they fall in the spectrum. As with many of their political positions, the differences aren’t too dramatic.

Here are some of the things we came up with when sizing up the top Democrats’ immigration positions, starting with Barack Obama …

- Obama has consistently said he supports a guest worker program.

- Obama has said he “will not support any bill that does not provide [an] earned path to citizenship for the undocumented population.”

- Obama does not believe that 12 million illegal immigrants can be sent back. He said “It’s not going to happen. We’re not going to go round them up … We should give them a pathway to citizenship.”

- In September 2006, Obama voted for the Secure Fence Act, authorizing the construction of 700 miles of fencing along the U.S.-Mexico border.

- In January 2008, perhaps in an effort to attract Lation votes, Barack Obama campaigned to grant drivers licenses to illegal immigrants.

Here are some notable Hillary Clinton immigration policy notes …

- On March 8, 2006, Hillary Clinton criticized H.R. 4437, a bill passed by the House of Representatives in December 2005 that would impose harsher penalties for undocumented workers. Clinton called the measure “a rebuke to what America stands for” and said it would be “an unworkable scheme to try to deport 11 million people.” She believed the solution to illegal immigration problems was to make “a path to earned citizenship for those who are here, working hard, paying taxes, respecting the law, and willing to meet a high bar for becoming a citizen.”

- On March 27, 2006, Hillary Clinton again vowed to block the bill, saying “[The bill] is certainly not in keeping with my understanding of the Scriptures because this bill would literally criminalize the Good Samaritan and probably even Jesus himself.” The bill was not passed by the U.S. Senate.

- In September 2006, Clinton voted for the Secure Fence Act, authorizing the construction of 700 miles of fencing along the U.S.-Mexico border.

- In May-June 2007, Clinton cast votes (in terms of amendments and cloture) in support of the high-profile, compromise-based but controversial, comprehensive immigration reform bill known as the Secure Borders, Economic Opportunity and Immigration Reform Act of 2007.

- On October 30, 2007, Clinton committed support of New York Governor Eliot Spitzer’s plan to give driver’s licenses to illegal immigrants. Two minutes later, she recanted the position and blamed the Bush administration for not passing immigration reform. The following day, she clarified her position in a prepared statement by coming out in support of Spitzer’s bill. Two weeks later, after Spitzer abandoned the plan, Hillary Clinton reversed her position on the issue once again, stating: “I support Governor Spitzer’s decision today to withdraw his proposal.”