House Republicans are spying a surprise opportunity to flip another Democratic-held district after the Laredo, Texas, home and campaign office of Texas Rep. Henry Cuellar were raided by the Federal Bureau of Investigation Wednesday.

Cuellar, 66, a centrist and frequent target of Republicans and the Left, has been impossible to dislodge since winning a seat in Congress in 2004. But Cuellar could be unexpectedly vulnerable beginning March 1, when he stands for renomination against a liberal challenger in the Democratic primary — or this fall, against a Republican, if it turns out the congressman is the target of a federal investigation and the inquiry extends deep into the election year.