Every 10 years state legislatures redraw congressional districts based on U.S. Census information. This year, the redrawn maps are forcing some longtime incumbents to run in unfamiliar and sometimes hostile territory.
In an article published Sunday, The Hill identified five Republicans who are believed to be most vulnerable:
-- Robert Dold, Illinois, who won a Democratic-leaning Chicago suburban district by a 3 percentage point margin. Redistricting made the district more Democratic.
-- Ed Royce, California, who likely will square off with fellow Republican Gary Miller in a primary to stay in Congress. California's new map has one less Republican district.
-- Judy Biggert, Illinois, who also saw her district greatly changed. The Hill said the centrist Republican would have a hard time winning a GOP primary in the few Republican-leaning districts left in greater Chicago and could retire.
-- David Dreier, California, whose district has a significantly higher Hispanic population than it did 10 years when Republicans redrew district lines. If Rep. Jerry Lewis, R-Calif., doesn't retire, Dreier could have to run in a district that that now leans strongly Democratic.
-- Jeff Landry, Louisiana, who could be sunk by his own party. Louisiana will lose a congressional district and the lone Democratic seat in the state is heavily African-American and protected by the Voting Rights Act, the Hill said. As Republicans work to protect their own in the redistricting plan, Landry could be odd-man out and likely could challenge Republican Rep. Charles Boustany in a primary.