Republicans waged a two-front fight this weekend -- in Wisconsin, which holds an important Tuesday primary that will set the tone for the presidential race in the next two weeks before New York votes, and at delegate-selection meetings across the country, where candidates are angling for a leg up in case the GOP holds a contested convention.
Here's a look at the political action heading into a week that could reshape the race:
Wins would give both campaigns shots of momentum. For Cruz, it's an especially important contest if he's to hold Republican front-runner Donald Trump
short of the 1,237 delegates he needs to win the GOP nomination. And for Sanders, it'd help him look viable headed into a spate of East Coast contests that Clinton's campaign hopes will seal her victory.
All five candidates blanketed Wisconsin over the weekend, each firing up supporters at their rallies. The main attractions were a Republican dinner in Milwaukee on Friday night, followed by a Democratic one Saturday night.
The most telling reception from Wisconsin voters could have been the chilly one given to Sarah Palin, who stumped for Trump at a Milwaukee County GOP event Friday night.
The audience, which had greeted Palin polite applause, hardly tried to hide its eye-rolls as she argued that Trump is the true conservative heir to Ronald Reagan. When Palin made her case for "Donald Trump's positions," a man in the audience jeered: "What positions?"
The delegate hunt
Trump can win 1,237 delegates and clinch the Republican nomination before the convention in Cleveland -- or he can be stopped. Either way, the math will be close.
Cruz made a visit to Fargo, North Dakota, where state Republican officials were choosing 25 delegates to the Republican National Convention on Sunday. These delegates could be especially important when the convention comes, because they're free agents -- unbound by state rules and able to vote for anyone.
Trump's campaign was furious when Tennessee, meanwhile, picked a slate of delegates that includes several choices who are obligated to back Trump through the Republican National Convention's initial two rounds of balloting -- but then would likely bolt for another candidate.
In Colorado, Cruz picked up all six delegates available in the first stage of the state's complicated selection process, shutting Trump and Ohio Gov. John Kasich
out of delegates from two congressional districts. Delegates from the state's other districts will be chosen Thursday and Friday.
Democrats get nasty
campaign strategist Joel Benenson's call a week ago for Sanders to improve his "tone" and focus his criticism on Republicans has backfired.
The front-runner and delegate leader would like to shift her focus to taking on Republicans in the general election. But Sanders isn't going away. He could win Tuesday in Wisconsin and he's competing hard in New York, which votes on April 19.
The two have also traded sharper exchanges in recent days, starting Thursday when Clinton told Greenpeace activists that she was "so sick of the Sanders campaign lying about me" taking fossil fuel industry donations.
Then, Sanders demanded an apology, saying his critique of Clinton is true.
A Washington Post fact-checker was critical of Sanders' assertions
, noting that both campaigns have received money from oil and gas industry employees, and that Clinton has benefitted from lobbyists who work for those industries -- but that those lobbyists have multiple clients, so it's inaccurate to cast their fundraising efforts as money "given" by fossil fuel interests.
Confronted with that fact-check, Sanders didn't back down Sunday.
"Let the voters decide whether paid lobbyists who represent the fossil fuel industry, 43 of them, gave maximum contributions to the Clinton campaign and whether or not these same people are out in some cases bundling, trying to bring in even more money," Sanders told CNN's Jake Tapper on "State of the Union."
In Eau Claire, Wisconsin, on Saturday, Clinton also beat up Sanders for only joining the Democratic Party when he launched his presidential campaign.
"I am also a Democrat and have been a proud Democrat all my adult life," Clinton said. "And I think that is kind of important if we are selecting someone to be the Democratic nominee of the Democratic Party."
Trump flip-flops on abortion, again
Trump had already angered both sides of the abortion debate last week when he suggested that women who undergo abortions should face "some form of punishment" if they were illegal -- and then reversed himself almost immediately, when the political danger of that position was apparent.
Then, on Friday, he did it again.
Trump set off his second abortion-related controversy in 72 hours when he told CBS News that federal laws should not be changed to outlaw abortion.
"At this moment the laws are set. And I think we have to leave it that way," Trump said.
Once again, Trump's aides were forced to backtrack, with spokeswoman Hope Hicks saying Trump was merely describing the state of play until he's elected president and can appoint judges who would turn abortion into a states'-rights question.
It was the latest episode in a string -- from his tepid answers to questions about white supremacists on CNN's "State of the Union" in late February to the incidents of violence that have surrounded his campaign events and staff -- that have given establishment Republicans reason to worry that Trump's nomination could have negative down-ballot effects, particularly if his sky-high disapproval rate among women doesn't improve.
Overall, 73% of female voters in a mid-March CNN/ORC
poll said they had a negative view of Trump, while just 26% view him positively.
Democratic debate watch
Increasingly, it appears Clinton and Sanders will debate again before New York's April 19 primary.
Both candidates say they are "confident" that their campaigns will find a workable date for a debate ahead of the New York primary.
But the two sides are not in agreement yet. While the Clinton campaign is aiming for the evening of April 14, the Sanders campaign is resisting that date.
"I'm not quite sure how that works on our schedule. We may have a major rally being scheduled," Sanders told CNN's Jake Tapper on "State of the Union."
Clinton brought up the April 14 proposal on NBC's "Meet the Press" and asked, "Is he in?"
"I'm confident that there will be" a debate before the April 19 primary, Clinton said, but added, "I'm not the one negotiating it. That's going on between our campaigns. And I do know my campaign has really been trying to get a time that Sen. Sanders' campaign would agree with."
CNN, NBC and ABC are among the networks seeking to host a debate between the two Democratic candidates.
Kasich under attack
He might not like to attack his Republican presidential rivals -- but Kasich is under siege himself.
Trump said he wants Kasich out of the race -- and he wants the Republican National Committee to make it happen.
"Kasich shouldn't be allowed to run. Honestly, Kasich should not be allowed to run," Trump told reporters while visiting a diner in Milwaukee, adding that Kasich takes more voters away from him than from Cruz. "Kasich shouldn't be allowed to continue, and the RNC shouldn't allow him to continue," Trump said.
He said he brought up the issue during his meeting with RNC Chairman Reince Priebus last week. "I said, 'Why is a guy allowed to run? All he's doing is he goes from place to place, and loses and he keeps running,'" Trump said. "He doesn't have to run and take my votes. Because he's taking my votes. He's not taking Cruz's votes."
Kasich spokesman Chris Schrimpf fired back, saying: "Ted Cruz also has no possibility of accumulating enough delegates and Donald Trump also will not receive a majority of delegates before the convention. Since he thinks it's such a good idea, we look forward to Trump dropping out before the convention."
That wasn't the only attack on Kasich, a candidate both Trump and Cruz view as a drain on their support. Cruz's campaign is hitting Kasich in Wisconsin with an ad accusing the Ohio governor of a conflict of interest that has benefited a company that laid off 100 workers.