On December 19, the U.S. House of Representatives passed HR 1, the tax bill. There are eighteen Republicans in the U.S. House from the two states that use the top-two system. Of those eighteen Republicans from California and Washington, all but two voted “Yes” on the bill. Here is the roll call. The two Republicans who voted against it are Dana Rohrabacher and Darrell Issa, both from southern California.
The vote must be re-done, due to a problem with the bill. The re-vote will be December 20. All Democrats voted against the bill.
Supporters of top-two system argue that in a top-two system, elected politicians vote without regard to the will of “party bosses” and instead vote in accordance with popular opinion. However, generally, that did not happen on December 19. All of the Republicans in open primary states voted for the bill. In New York, which has closed primaries, five Republicans voted against the bill; in New Jersey, which has closed primaries (except independents can join a party on primary day if they wish to vote in a primary), four of the five Republicans voted against the bill; in North Carolina, which has semi-closed primaries, one Republican voted against the bill.
This outcome confirms what political science research has shown: type of primary system does not change how elected politicians behave.