Confused and frustrated, a growing number of Democrats are blaming their own party as they seek to avert a drubbing in Tuesday’s congressional primaries here that would leave their candidates shut out of the November ballot in some races — and with a narrower path to win control of the House of Representatives.

In three Orange County districts, a surfeit of enthusiastic candidates and conflicting messages from Democratic organizations and allies have converged to complicate the party’s road to victory. All three districts are held by Republicans, and all three are widely seen as crucial to Democratic efforts to pick up the 23 seats they need nationwide to win the House majority.

Democrats have had internal conflicts in other states, but the circumstances in California are far more convoluted because of the state’s “top two” nominating system, in which the two highest vote-getters are elevated to the November ballot, irrespective of party affiliation. Two Democrats could make the general election ballot — or two Republicans, as happened in a 2012 House race.