Emboldened by last month's triumphs in Wisconsin, Republicans are already sizing up their next big target, taking on Democratic U.S. Sen. Tammy Baldwin in 2018.

The race against Baldwin is expected to be among the fiercest in the next election cycle. Senate Democrats have to defend 23 seats nationally.

Republicans are eager to turn Wisconsin a bright shade of red, building on the momentum of 2016 wins by President-elect Donald Trump and Republican U.S. Sen. Ron Johnson.

The field of Republican runners is expected to take shape over the next six months, with potential candidates trying out their lines for the party faithful at Lincoln Day dinners in February.

//State\\ Senate Majority Leader Scott Fitzgerald of Juneau told the //Milwaukee\\ Journal Sentinel that he is considering making a run.

GOP operatives said at least four people are weighing the race — U.S. Rep. Sean Duffy of Wausau; state Sen. Leah Vukmir of Wauwatosa; Eric Hovde, who finished second in the 2012 GOP Senate primary; and Marine veteran and businessman Kevin Nicholson.

Lt. Gov. Rebecca Kleefisch's //name\\ has also been mentioned as a possible runner, along with state Rep. Dale Kooyenga of Brookfield.

"My focus is getting a laundry list of items done in this next legislative session," Kooyenga said.

Mark Graul, a political operative, said: "The names swirling around are very strong candidates," but he cautions that it is next to impossible to predict the 2018 political landscape.

"Right now, the most important thing for Republicans in Washington is to deliver on the mandate that they received from voters and that will tell a lot about the kind of success they'll have in a general election," Graul said.

Fitzgerald said he wants to avoid what occurred in 2012 when his brother Jeff, then the Assembly speaker, was part of a contentious four-way GOP primary. Former Gov. Tommy Thompson had to spend precious time and money to win the primary. He then fell to Baldwin in the general election.

"There was a real opportunity last time that just kind of slipped away," Fitzgerald said.

The potential candidate who everyone appears to be waiting on is Duffy, who raised his profile this year when he became an early backer of Trump. First elected to Congress in 2010, he represents the district held for years by Democrat Dave Obey.

If Duffy enters the race, Fitzgerald said: "The party should unify behind him."

Other candidates have strengths, too.

Hovde has the ability to self-fund his campaign and gave Thompson a strong run in 2012. Vukmir is well-known in southeastern Wisconsin and has risen to leadership in the state Senate. Fitzgerald jumped on the Trump train early and united Republicans who initially weren't thrilled with their presidential candidate.

Kleefisch is well-liked by the Republican base and is a strong fundraiser. Kooyenga is a proponent of school reform, which is especially popular among Republicans. Nicholson served tours in Iraq and Afghanistan and is on the Wisconsin Board of Veterans Affairs.

Pat Garrett, spokesman for the Republican Party of Wisconsin, spokesman Pat Garrett said: "Wisconsin Republicans have a deep bench of highly respected candidates that will each give voters an alternative to Senator Tammy Baldwin and her radical, out of touch voting record. Republicans are focused on issues that matter to Wisconsin families and will set a clear contrast to Baldwin's record of putting politics before people."

Baldwin isn't just sitting still. She was a constant presence on the campaign trail in 2016 as a surrogate for Democratic presidential candidate Hillary Clinton and senate candidate Russ Feingold.

She joined the Senate Democratic leadership team giving her a chance to shape the party's message and set priorities. And she has sought to stake out positions to help Wisconsin manufacturing.

In the race, she'll try to tap into so-called Baldwin-Trump voters. In 2012, Baldwin won 13 counties that Trump won in 2016.

"Tammy has traveled across the state and listened to the concerns of workers and small business owners," said Baldwin's political director, Scott Spector. "She understands that they feel their voices are not being heard and Washington isn't working for them. That's why Tammy will stand up to the corporate lobbyists, big banks and Wall Street moguls that are now calling the shots in Washington."