Reps. Donna Edwards & Chris Van Hollen
One unusual aspect of Maryland's Senate race is that seven of the state's eight members of the House are either contemplating bids or, in the case of Reps. Chris Van Hollen and Donna Edwards, are actually running to succeed retiring Sen. Barbara Mikulski. While others are also considering the contest, this congressional crop of candidates will form the top tier of contenders, and because they've all served on Capitol Hill, we can directly compare their ideologies using the
DW-Nominate system pioneered by University of Georgia Prof. Keith Poole.
Political scientists generally regard DW-Nominate as the gold standard when it comes to evaluating overall ideology because it relies on every single vote cast in Congress, not just a select few. It also has another advantage: By looking at the records of the several hundred lawmakers who have served in both the House and the Senate, it's possible to come up with scores that treat both chambers as a single legislature. In other words, these "Common Space scores" allow direct comparisons between senators and representatives, even though the two bodies often vote on different pieces of legislation (and follow different rules of procedure).
With all that in mind, we've put together an ideology chart for Maryland's entire delegation, including retiring Sen. Barbara Mikulski, fellow Sen. Ben Cardin (who isn't up for re-election until 2018), and Rep. Steny Hoyer, the only Democrat who definitely won't run for Mikulski's seat:
As you can see, Edwards is by far the most liberal of the bunch, which is not too surprising since she also represents
the bluest district in the state. But district demographics don't necessarily translate perfectly into ideology: John Sarbanes' seat gave 61 percent of its vote to Barack Obama, but he's a touch to the left of Elijah Cummings, whose district is comparable to Edwards' (76 percent Obama versus 78 for Edwards).
And while Van Hollen has spent his career as an establishment player, he's also slightly to the left of Mikulski, who is generally regarded as a very solid liberal. Meanwhile, at the far right of the chart is Maryland's lone Republican congressman, Rep. Andy Harris, so you can see just how far out-of-step he is with the rest of the delegation. Harris would probably be the GOP's best get for this race, but considering that Obama carried the Old Line State by a 62-36 margin, Harris will almost certainly prefer to stay in his safely red seat.