Donald Trump and Hillary Clinton are looking beyond their struggling primary-season rivals and focusing on the one-on-one battle to come if they sew up the Republican and Democratic presidential nominations.
Read more: Donald Trump targeted by US May Day protesters
Mr Trump, campaigning on the eve of Indiana's primary, made clear that he will have more to say about his accusation that Mrs Clinton is playing gender politics: "We're making a list of the many, many times where it's all about her being a woman."
The billionaire also told CNN: "I haven't started on Hillary yet," although he has actually been attacking her record for quite some time.
Read more: Donald Trump makes case in California as protesters clash with police
For her part, Mrs Clinton told thousands at an NAACP dinner in Detroit on Sunday that US president Barack Obama's legacy cannot be allowed to "fall into Donald Trump's hands" and be consumed by "these voices of hatred".
She cited Mr Trump's "insidious" part in the so-called "birther" movement which questioned Mr Obama's citizenship.
But the front-runners still have party rivals to dispatch. Mr Trump's next challenge is to beat senator Ted Cruz in Indiana on Tuesday. He has further to go win the prize than Mrs Clinton in her contest with Bernie Sanders.
Read more: Donald Trump says victory in Indiana means Republican race is 'over'
Mr Trump is exuding confidence, telling a cheering crowd in Terre Haute: "If we win here, it's over, OK?"
This is not quite the case, as the New York real estate mogul cannot win enough delegates on Tuesday to clinch the Republican nomination. But after his wins in five states last week, Mr Trump no longer needs to win a majority of the remaining delegates in coming races to lock up the Republican nomination.
Mr Cruz has no such cushion. Already eliminated from reaching 1,237 delegates needed to win the nomination outright, he desperately needs a victory in Indiana to keep Donald Trump from that number and press ahead with his strategy of claiming the nomination at a contested convention in Cleveland this summer.
"This whole long, wild ride of an election has all culminated with the entire country with its eyes fixed on the state of Indiana," Mr Cruz said at a late night rally.
"The people of this great state, I believe the country is depending on you to pull us back from the brink."
The importance of Indiana for Mr Cruz became evident even before he and fellow underdog John Kasich formed an alliance of sorts, with the Ohio governor agreeing to pull his advertising money from Indiana in exchange for Mr Cruz doing the same in Oregon and New Mexico.
But that strategy, which appeared to unravel even as it was announced, cannot help either man with the tens of thousands of Indiana voters who had already cast ballots: early voting began in Indiana three weeks before they hatched their plan.
It also risks alienating those who have yet to vote, according to veteran Indiana Republican pollster Christine Matthews. She said she believes many have continued to vote for Mr Kasich in Indianapolis and in the wealthy suburbs north of the city.
"Indiana voters don't like the idea of a political pact, or being told how to vote," Ms Matthews said.
Mr Trump suggested evangelical conservatives have "fallen out of love" with Ted Cruz, and mocked his decision to announce former Republican presidential candidate Carly Fiorina as his running mate.
"They're like hanging by their fingertips," he said, mimicking Mr Cruz and Mr Kasich: "Don't let me fall! Don't let me fall!"
Mr Trump admitted he is eager to move on to a likely general election race against Mrs Clinton.
He said the end game of the primary battle with Ted Cruz is "wasting time" that he could be spending raising money for Republicans running for the Senate.
"It would be nice to have the Republican Party come together," Mr Trump told supporters in Fort Wayne.
"With that being said, I think I'll win anyway."
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here