Former governor Bob Ehrlich knows he’s tilling tough ground in his race against incumbent Martin O’Malley, and he won’t hesitate to remind voters.

Maryland is "the bluest state in the country," the Republican has said multiple times during rallies, speeches and debates in recent weeks.

No one doubts that Maryland has been unfriendly territory for Republicans. When Ehrlich took office as governor in 2002, he was the first member of the GOP to hold the office since Spiro Agnew in the late 1960s (and the first non-corrupt GOP member to hold it since Theodore McKeldin, who held the office for most of the 1950s). Seven of the state’s eight U.S. House districts -- thanks in part to a friendly redistricting process in 2000 -- are in Democratic hands. A Republican hasn’t been attorney general since 1954. The state hasn’t seen a GOP comptroller since 1900. Democrats hold a two-to-one edge in voter registration, and a massive edge in the General Assembly.

Though Ehrlich convinced Democrats to break party ranks in 2002, he’s having a bit more difficulty this year. Two recent polls have him down 14 points.

Even with all that, Ehrlich’s depiction of Maryland as the bluest of the blue intrigued The Facts Machine. What about Massachusetts? Or California, with liberal bastions like San Francisco and Los Angeles? The Hippie-Farmer paradise of Vermont? Or Illinois, home of the current president and the formidable Chicago Democratic machine?

Judging “blueness” is more difficult than you think. To start, there’s a difference between a state being heavily liberal and a state being heavily Democratic. While ideology and party identification track one another, they aren’t synonymous. (The best example of this is probably West Virginia, which usually elects Democrats to statewide positions but goes for conservative Republicans in presidential races.)

Let’s also dispatch with one easy answer. The District of Columbia isn’t a state, so we won’t include it here.

So how do we rate blueness? Luckily, a few rating systems already exist. The most popular is probably the Cook Political Report’s Partisan Voter Index, which measures how strongly states and congressional districts lean towards one party or the other.

Using data from the 2004 and 2008 presidential elections, Maryland has a score of +9 Democratic, trailing Vermont, Hawaii, Massachusetts, Rhode Island and New York.

That's one way of measuring it, but maybe the Old Line State has seen a new surge of liberal voters in recent years that Cook hasn't picked up on. So let's look at another measure.

According to daily Gallup tracking polls taken from January to June of this year, Maryland had a 22 percentage point Democratic edge in party identification, trailing only Vermont, which has a 26 point edge.

Strike two.

Of course, there are elements to liberalism election results don't reflect. Policy outcomes in Vermont and Massachusetts — both of which have legalized gay marriage and have extensive taxpayer-funded health care programs — provide further evidence for the argument that those states are more liberal than Maryland.

Each state also has its own unique political history and traditions. Maryland has a strong history of conservative Democrats working to moderate the tendencies of legislators from Baltimore City and the Washington suburbs. At the same time, the state's large black population makes it a more difficult Republican pickup since blacks tend to have stronger Democratic partisan identification than white voters.

In comparison, Massachusetts has a history of liberal-to-moderate Republicans that Maryland seems to lack. (That's why Massachusetts elected Republican governors from 1990 to 2006.)

In the end, Ehrlich's statement is only a slight exaggeration. Looking at both policy outcomes and election results, Maryland doesn't top the liberal pile, but it's among the bluest. Unfortunately, The Facts Machine frowns upon inappropriate use of the superlative. Ehrlich gets a Total Malarkey.