Virtually every House Democrat listed as vulnerable by Rothenberg Political Report/Roll Call voted for Republican Michigan Rep. Fred Upton’s Keep Your Health Plan Act.

Two vulnerable Democrats voted against the bill: Ann Kirkpatrick of Arizona and John F. Tierney of Massachusetts.

Overall, 39 Democrats joined with the vast majority of Republicans in order to pass the bill; 23 of those 39 Democrats are rated as vulnerable to some degree. Unlike their fellow delegate Kirkpatrick, Arizona Reps. Ron Barber and Kyrsten Sinema voted for the bill.

What’s also striking about Kirkpatrick and Tierney is how different their districts and political situations are.

Kirkpatrick was elected to Congress in 2012 with 49 percent of the vote after losing re-election in 2010. Arizona’s 1st District is currently rated Toss-Up/Tilts Democrat, according to Rothenberg Political Report/Roll Call.

In contrast, Barack Obama and John Kerry carried Massachusetts’s 6th District with at least 55 percent in the last three presidential contests. But Tierney faces an increasingly serious challenge in the primary, and the congressman could be concerned that supporting any effort to delay or derail the president’s signature piece of legislation could hurt him with a Democratic electorate.

Tierney is also likely to face a competitive rematch against Republican Richard Tisei in the general election. The congressman was re-elected to a ninth term in 2012 by defeating Tisei by 1 point. Massachusetts’s 6th District is currently rated Leans Democrat by Rothenberg Political Report/Roll Call.