Last year, Democrats spent millions of dollars elevating far-right candidates in Republican primary contests for governor and Congress — betting, it turned out correctly, that more extreme opponents would lose general elections.
Now Wisconsin Democrats are trying to do it again, this time with mail and TV ads before a Republican primary in a special election for a State Senate seat that carries ramifications far beyond the district in suburban Milwaukee.
The Democrats are helping a far-right election denier who has become a pariah within her party in her race against a less extreme, but still election-denying, conservative. They hope that with a more vulnerable opponent, Democrats can win a seat held for decades by Republicans and deny the G.O.P. a veto-proof majority in the gerrymandered chamber.
“Janel Brandtjen is as conservative as they come,” reads a postcard sent to Republican voters from the Democratic Party of Wisconsin, which calls her “a conservative pro-Trump Republican.”
The Feb. 21 primary, and the April 4 general election to follow, will serve as the latest test of how much appetite Republican voters have for the flavor of election denialism that fueled the party’s grass roots after former President Donald J. Trump’s 2020 election loss.
The twist in the Wisconsin race is that both leading Republican candidates took significant public steps to try to overturn Mr. Trump’s defeat. One of them, however, Ms. Brandtjen, a state representative from Menomonee Falls, has so alienated members of her own party that she was kicked out of the State Assembly’s Republican caucus, leaving Democrats giddy about the prospect of facing her in a special election for a battleground district.