WASHINGTON (Reuters) - President Barack Obama said on Wednesday that Democrats risked punishment in November's congressional elections if they allow the vote to be just about the U.S. economy, rather than the two parties' policies.

"My challenge, and the challenge of every Democratic candidate who is out there, is just making sure people understand that there is a choice here," Obama told ABC News in an interview taped earlier in Cleveland. The full interview will be aired on ABC's Good Morning America on Thursday.

Opinion polls show Republicans likely to do well in the November 2 elections in which all 435 seats in the U.S. House of Representatives and 37 of the 100 seats in the Senate are up for grabs. Some estimates see them winning control of both houses of Congress from Democrats.

"If the election is a referendum on 'are people satisfied about the economy as it currently is,' then we're not going to do well, because I think everybody feels like this economy needs to do better than it has been doing," Obama said.

(Reporting by Alister Bull; Editing by Peter Cooney)