In 1910, Victor L. Berger, an Austrian-born Jew, was elected to Congress from Wisconsin. He served out his two-year term, then ran again. And lost. Three times.

Fourth time proved to be the charm, as he was re-elected in 1918. Perhaps "charm" isn't the right word here. In an unprecedented move, Congress refused to seat Berger. He was one of the first victims of the Espionage Act of 1917, for having the gall to state that the US shouldn't have interfered in World War I. Perhaps being a socialist (the first ever in US Congress) played a role?

So Wisconsin held a special election in 1919, which... Berger won again. The House, on cue, refused to seat him again. The gall of a man to speak against war! A war that was already over by then...

In 1921, the Supreme Court overturned Berger's conviction, so he promptly ran a year later, won again, served three straight terms, then lost and retired from politics to go back to his first love, journalism.

And socialists have been welcome in US Congress ever since!