Republicans -- 42 delegates
Donald Trump has had some media stumbles of late, but the headlines will get worse if he loses Wisconsin and his path to 1,237 delegates narrows.
It's close, but Ted Cruz has led in most polls here and is now attacking John Kasich as a way to consolidate the anti-Trump vote. One factor in Trump's favor is the fact that Wisconsin holds an open primary, and the billionaire has done well with voters who are not pre-registered Republicans.
Wisconsin is not pure winner-take-all, but a delegate sweep is quite possible. The winner gets 18 delegates, and the winner of each of the state's eight congressional districts gets three delegates. There's no prize for second.
One recent poll had Cruz winning in every media market except college-town Madison, where Kasich narrowly edges Trump. So keep an eye on the Madison-based Second Congressional District tonight.
Democrats -- 96 delegates
Try as she might to shift to the general election with broadsides against Trump, Hillary Clinton does still have a primary -- and a feisty foe who is not going away.
Bernie Sanders is on a roll, taking five of the last six states, and he has a shot in Wisconsin with polls giving him a slight advantage. From the liberal core in Madison to disaffected rust-belt workers, it sets up well for Sanders.
But Democrats' proportional allocations mean that it is a long process to chip away at Clinton's healthy delegate lead. Because Sanders' recent wins have been in less delegate-rich states, he has not been able to draw close yet. A convincing Wisconsin win would be a coup for him, even as the math favors Clinton.
Both are competing hard in the state, though Sanders has spent more time there. Clinton will be trying to run up the score in African-American-heavy Milwaukee, with Sanders charging in Madison and elsewhere.
Polls: ARG (April 1-3): Trump 42, Cruz 32, Kasich 23; Clinton 49, Sanders 48. Emerson (March 30-April 3): Cruz 40, Trump 35, Kasich 21; Sanders 51, Clinton 43. CBS News/YouGov (March 29-April 1): Cruz 43, Trump 37, Kasich 18; Sanders 49, Clinton 47. Fox Business (March 28-30): Cruz 42, Trump 32, Kasich 19; Sanders 48, Clinton 43.
Candidate visits: Sanders was in Sheboygan and Green Bay on Friday; Eau Claire and Milwaukee on Saturday; Wausau and Madison on Sunday; Janesville, Green Bay and Milwaukee on Monday.
Clinton was in Eau Claire and Milwaukee on Saturday. Bill Clinton was in Appleton on Friday and Milwaukee on Monday.
Trump was in Racine, Wausau and Eau Claire on Saturday; West Allis on Sunday; La Crosse, Superior and Milwaukee on Monday.
Cruz was in Milwaukee on Friday; Ashwaubenon on Saturday; Green Bay and Eau Claire on Sunday; Madison, Kenosha, Milwaukee and Waukesha on Monday. He is also holding an election night party in Milwaukee -- a sign of confidence in the outcome.
Kasich was in Milwaukee on Friday; Burlington, Janesville and Madison on Saturday.
Links: Digging deeper into Wisconsin numbers shows trouble for Trump. (FiveThirtyEight)
Wisconsin Gov. Scott Walker's energetic support for Cruz suggests his political career is not done after his early presidential exit. (Politico)
A white nationalist group robocalled every landline in Wisconsin urging support for Trump. (Milwaukee Journal-Sentinel)
As he struggles with women, Trump brought his wife, Melania, to Milwaukee for a rare campaign trail appearance. (New York Times)
Campaigning in Madison, Sanders said marijuana use should not be a federal crime. (ABC 13)
Both Clinton and Sanders are selling themselves as the anti-Walker, who is loathed among Wisconsin Democrats. (Mother Jones)