The surprising announcement last month by Rep. Sean Duffy (R-WI) that he will resign from Congress on September 23 sets the stage for yet another special election in a Republican-held district that Democrats hope to flip from red to blue.

As the Wausua Daily Herald reported on August 30:

In a normally Republican stronghold, Democratic candidates are eyeing the 7th Congressional District after U.S. Rep. Sean Duffy announced he will be resigning next month. Duffy, a Wausau-based Republican who has represented the district since 2011, said Monday he will be leaving Congress in September to spend more time with his growing family after learning his ninth child will be born with a heart defect. Duffy will be replaced in a special election, for which Gov. Tony Evers has yet to set a date. Duffy said in a Monday Facebook post that he will step down on Sept. 23. Several candidates from both the Democratic and Republican parties have expressed interest in the seat, but only Spencer Zimmerman has declared his candidacy. In an email, Zimmerman said he won’t decide which party he’ll represent until he knows who the Democratic presidential nominee appears to be.

Duffy’s announcement came just weeks before voters determine the results of the hard fought September 10 special election in North Carolina’s Ninth Congressional District. The seat has been empty since the 116th Congress convened in January, but was represented in the 115th Congress by a Republican, former Rep. Robert Pittenger (R-NC). The most recent polls in that district show the race between Republican Dan Bishop and Democrat Dan McCready is too close to call.

First elected in 2010, Duffy easily defeated his Democrat opponent, Margaret Engebretson, in the 2018 midterms, 60 percent to 48 percent.

Though the Cook Report’s Partisan Voting Index (PVI) for Wisconsin’s Seventh Congressional District is Republican plus 8, Democrats are pondering whether Republicans will be able to field a candidate as well tuned to the district as Duffy, a rising star among Republicans in the House until his surprise resignation. Indeed, Duffy’s path to GOP House leadership seemed secure, as he served as the chairman of the important Oversight and Investigations Subcommittee of the powerful House Financial Services Committee during the 114th Congress.

State Senator Jerry Petrowski, a Republican, is among several potential candidates considering the race to replace Duffy, the Daily Herald reported on Wednesday:

Wisconsin State Sen. Jerry Petrowski said Wednesday he is considering a run for the state’s 7th Congressional District after U.S. Rep. Sean Duffy’s early departure. He’s among at least six potential candidates for Duffy’s seat, which the congressman is leaving in September to help care for the newborn he and his wife are expecting in October. Petrowski, a Marathon County Republican first elected to the Legislature in 1998, released a statement that said he’s received hundreds of calls, text messages and emails asking him to run for the vacated seat, and that he’s overwhelmed by the support. “This is not a decision to take lightly,” he said in the email. “And I will be discussing options with my family over the next couple of weeks.”

Gov. Evers is expected to make a decision on the date of the special election soon, as the Associated Press reported last week:

Democratic Wisconsin Gov. Tony Evers says he’s awaiting a recommendation from his legal team about when to call a special election for the congressional district being vacated by retiring Republican Rep. Sean Duffy. Evers said Thursday that he doesn’t know if he’ll have the special election correspond with the state’s presidential primary in April, when there’s also a state Supreme Court election. Duffy announced Monday that he plans to resign Sept. 23 due to heart defects detected in the baby his wife is due to deliver in October. Evers says it is “relatively early in the process” but hopes to make a decision soon.

As soon as Evers announces the date, the special election in Wisconsin’s Seventh Congressional District is likely to attract huge spending from both Democrats and Republicans, as it will be seen as another bellwether of the 2020 general election.