National Journal: The Top 10 Lawmakers Who Could Lose a Primary Next Year

Incumbency in Congress is a fortress rarely breached, particularly in primaries. In the 2012 elections, even amid record-low approval ratings, primary voters tossed only one senator and five members of the House from office (not including those races featuring two incumbents sqauring off because of redistricting).

The odds are clearly in favor of the members. Still, primary voters give the boot to at least some lawmakers nearly every cycle. For those facing electoral threats from within their own party, the pressure is especially acute as they return to their districts and states for the August recess. This month marks one of the better, prolonged periods for them to make a positive impression back home.

With his brother-in-law sent to prison and allegations swrling that his wife was involved in an illegal offshore gambling ring, Rep. John Tierney narrowly won reelection last November, despite running in an overwhelmingly Democratic district. This time, he's got a serious primary challenge—with two candidates already in the race. One, Seth Moulton, is a former Marine with three degrees from Harvard and a strong campaign team, including Democratic strategist Joe Trippi and Max Glass, who managed Rep. Tulsi Gabbard's campaign in Hawaii last cycle. Also in the race is Marisa DeFranco, who waged an unsuccessful Senate primary against Elizabeth Warren last year. As of the end of June, Tierney had $376,000 banked. Republicans are watching closely, hoping that Tierney emerges even bloodier than before from the Democratic primary.

Read the original National Journal article here.