Virginia Delegate Sam Rasoul (D-Roanoke) has filed a 2017 bill to convert all partisan elections (except presidential elections) to a top-two system. It is HB 541 and is a proposed constitutional amendment. See this story. The story is incorrect when it says that Nebraska and Louisiana have top-two systems. Louisiana has abolished primaries (except presidential primaries) and only has a general election. In the few cases when no one gets a majority, there is a run-off. Louisiana does not vote for Congress until November. Nebraska has semi-closed primaries for all partisan office. Because Nebraska has non-partisan elections for the State Senate, proponents of top-two frequently claim Nebraska has a top-two primary, but that claim is incorrect.
Currently Virginia has open primaries. The voter registration form in Virginia does not ask the applicant to choose a party or independent status. So on primary day, any voter can choose any party’s primary ballot.
If the United States had a top-two system for president, the only candidates who would be allowed to run in the general election this year would be Donald Trump and Hillary Clinton.