On Friday, Maryland became the sixth state in six years and the 18th state in the country to repeal the death penalty. Gov. Martin O'Malley (D) lobbied hard for the legislation and will soon sign it.

The governor has framed the repeal in pragmatic terms, calling the death penalty an expensive policy that is "proven not to work." He's also hardly new to the issue; he wrote a Post op-ed back in 2007 called: "Why I Oppose the Death Penalty." But O'Malley is considered a very likely presidential candidate in 2016, and anything he does in office -- including this ban -- has implications for his political future.

Maryland Gov. Martin O'Malley speaks at a rally in support of repealing the state's death penalty in Annapolis, Md., Tuesday, Jan. 15, 2013. (AP Photo/Patrick Semansky)

So, is O'Malley on the leading edge of a movement whose time has come (or will come by 2016)?

Advocates think/hope so. “Maryland is the bellwether for the country on the death penalty,” said National Coalition to Abolish the Death Penalty Executive Director, Diann Rust-Tierney in a statement.

But, polling tells a more complicated story about the politics surrounding the issue.

Nationally, a 2011 CNN poll found for the first time that a bare majority, 50 percent, would prefer a murderer be given a life sentence over the death penalty. Forty-eight percent disagreed. But the poll did not ask about repeal. Gallup found in early 2013 that death penalty support is "stable" at 63 percent:

Gallup Polling chart.
Chart courtesy of Gallup Polling.

The death penalty's popularity has been gradually decreasing since a peak in the mid 1990s when a whopping 80 percent favored executions. Decreasing crime and increasing DNA evidence appear to have had an effect. But support has been stuck in the mid-60s for the past few years. There is no huge generational gap either -- as 61 percent of voters 18 to 34 back the death penalty. (But there is a racial gap that could come into play as the white share of the vote declines -- according to the General Social Survey, 56 percent of Hispanics and 47 percent of African-Americans back the death penalty, compared to 71 percent of whites.)

In Maryland, a strongly Democratic state, a majority supports the death penalty -- even though 61 percent of voters don't think it deters murder. It could end up on the ballot next year, as same-sex marriage and the state's version of the DREAM Act did last year.

"Anyone who's seen the polling on the death penalty knows that Governor O'Malley's not taking this issue on for political reasons," a political adviser to the governor said. "He took on repeal because it's the right thing to do."

At the same time, the death penalty itself has quietly waned. Executions are down 75 percent since 1996, according to the Death Penalty Information Center. Only nine states executed inmates in 2012, and four states -- Texas, Oklahoma, Mississippi and Arizona -- were responsible for three-quarters of those executions. President Obama supports the death penalty under narrow circumstances (a prior opponent, he changed his mind before the 2004 Senate campaign). But in 2012, for the first time, both presidential candidates came from states where the death penalty had already been abolished. The issue never came up in the campaign.

The death penalty simply isn't on the national radar in the same way as gay marriage or abortion. There is no prominent national lobby pushing for the death penalty, as there is for gun rights.

So O'Malley probably shouldn't fear a huge backlash on this issue, though it will likely be one of many Republicans would use to tag him as a liberal from a liberal state. On the flip side, it will score him a few points with the Democratic base but isn't going to propel him to national stardom.