Could a congressional candidate who lost a primary run as an independent, win the general, and then switch parties?

Question

I was thinking about progressive candidates and how Democratic primaries are a powerful tool that has successfully been used to install progressive candidates by replacing an "establishment" candidate with a "progressive" one. I was thinking of a variant of Bernie Sanders though surprisingly he did not do the opposite. The idea is this:

1. The challenger loses the primary narrowly.
2. The challenger runs as an independent and vows to switch to being a Democrat if elected in the general.
3. The challenger wins the general.

Is the challenger able to easily switch to being a Democrat? If so, when is the soonest that they could change parties? What mechanism could they use to switch parties?

Note: I chose the Democratic Party because the Republicans do not have this type of intra-party fight that I am describing at this level. This is also not asking about whether or not the challenger wins, because I already said yes, and he/she got a narrow plurality of votes.

Answer 1

Unfortunately, your idea would be likely to fall foul of 'sore loser' laws, enacted in most states with the general intention of preventing unsuccessful candidates in one party's primary from running either as a candidate of another party or as an independent candidate.

These laws have been enacted by most states in some form - according to Sore Loser Laws and Democratic Contestation (2011) - in all states apart from Connecticut, Iowa & New York. In addition, the article identifies Florida and Vermont as states where it is potentially possible to run as an independent, or 'no-party' candidate, as well as participating in a party primary. However, both of these states have deadlines for filing candidacy which would require the candidate to file as an independent candidate before the results of their chosen party's primary were known, which would presumably hurt their chances of winning the primary in the first place.

Assuming, then, that your hypothetical candidate was successful in contesting a congressional election as an independent in one of these states, joining the Democratic caucus seems to be as simple as registering as a Democrat. According to Rule 1 of the House of Representatives' Democratic Caucus Rules:

A. All Members of the House of Representatives, the Resident Commissioner from Puerto Rico, and the Delegates from American Samoa, the District of Columbia, Guam, the Northern Mariana Islands, and the Virgin Islands who are Members of the Democratic Party shall be prima facie Members of the Democratic Caucus of the House of Representatives.

This appears to also be the case in the Senate - for example, in 1955, when independent Senator Wayne Morse joined the Democrats, it seems to have been as simple as him registering as a member of that party. It is worth noting, however, that Morse was welcomed by the Democratic leadership - had he just defeated an official party candidate by frustrating the party's primary process, this would presumably be more of an issue, especially as the House Democrats' Caucus Rules also allow members to be expelled by a two-thirds majority vote.

Answer 2

If by "Democrat", you mean their party affiliation, anyone can register as whatever party they want whenever they want (although if they do it too close to a primary election, they may not get the new party's ballot).

But you seem to think that government officials have some sort of official status with respect to their party. They do not. There is no sense, as far as legally salient official designation is concerned, that Trump is a "Republican" president. Trump's relationship with the Republican Party is simply that he won their nomination. This means that he is endorsed by them on ballots, and the corresponding electors are expected to vote for him. Once the election is over, he no longer has any official relationship by virtue of that nomination.

If someone runs and wins as an independent, then they are not have not been the Democratic nominee. Before the election, they are not the Democratic nominee, and after the election, their political affiliation has no legal force with respect to their office.

If you're asking "But will they be listed as a Democratic official? For instance, will history books list them as such?", that's up to the writer of the history book. They can call them whatever they want. There are social norms that will likely factor into it, such as how soon and how prominently they identify as Democratic, how much they support positions seen as "Democratic" positions, whether Democrats accept them as being a Democrat, etc., but there is no official rule.

Answer 3

The case of Lisa Murkowski (R-AK) is instructive here. Murkowski was appointed to the US Senate in 2002 to fill a vacancy left by her father, Frank Murkowski (who resigned). She successfully ran for the seat again in 2004, but was defeated in the 2010 primary. But even though she lost the Republican nomination, she mounted a successful write-in campaign and was reelected Senator regardless. No switching parties was involved, and even though Murkowski didn't have the blessing of the GOP, she was still considered a member of the party.

Skirting sore-loser laws to sign up with a different party is, I imagine, technically possible, but difficult. As Wikipedia points out, Gary Johnson almost succeeded in 2012; he was a mere three minutes late withdrawing his nomination as a Republican candidate, and so was barred from appearing on the ballot as a Libertarian candidate. Write-in candidates can be certified fairly late in the game, so it is a viable alternative for someone who loses a primary, but it has risks: the candidate loses the support and resources that come with a party affiliation, and risks splitting the party vote, creating an opportunity for the opposing party.