People often back political candidates who work against their economic interests, but who win their support for other reasons, including race, religion, militarism, nationalism, scapegoating, etc. Blaming China for U.S. poverty, or opposing the TPP and the WTO, or promising fewer wars or the abolition of NATO -- these are economic positions, but they are something else as well.
Other people back political candidates who work against their economic interests, but who appeal to other needs. The Democrats are framing themselves as the inclusive, loving, multicultural, corporate militarist party, in contrast to the angry, white, bigot, corporate militarist party. Talking about equal (low) pay for equal work, and paid family leave, support for people with disabilities, equal rights for LGBTQ people, etc. -- these are economic positions, and the Democrats defend them as supposed engines of economic growth, but they are something else as well.