The seat of Representative Darrell Issa, a Republican whose California district Democrats redrew to lean Democratic, is among those added to the Democratic Congressional Campaign Committee’s list of “districts in play.”
The dispute before the court involved a Republican effort to lift limits on how much money political parties can spend in coordination with candidates.
In 2010, in the landmark case Citizens United v. Federal Election Commission, the Supreme Court struck down legal limits on independent political spending by corporations and unions.