Republican presidential front-runner Donald Trump is strengthening his top team and refocusing on New York after recent tactical failures raised doubts about his campaign.
The billionaire announced that veteran operative Paul Manafort would be taking on an expanded campaign role as the chances grow of the Republican nomination being decided by a contested party convention.
The move follows Mr Trump's loss this week in Wisconsin to rival Ted Cruz, which makes it increasingly unlikely that Mr Trump will be unable to collect the 1,237 delegates needed to win the nomination before the national Republican convention.
The addition of Mr Manafort to Team Trump also signals a less prominent role for campaign manager Corey Lewandowski, who was recently charged with simple battery over an incident with a female reporter in Florida.
Mr Trump said: "The nomination process has reached a point that requires someone familiar with the complexities involved in the final stages."
Mr Manafort has worked on conventions for presidents Gerald Ford, Ronald Reagan and George HW Bush.
Mr Trump's unconventional campaign operation is known for being unusually small and insular.
There are no pollsters, no media consultants and few outside policy advisers, with the candidate determining much of the messaging himself.
Mr Trump is now focusing on the April 19 primary in his home state of New York, where early opinion polls show him with a commanding lead.
His team has cleared his schedule, cancelling planned trips to California and Colorado.
On the Democratic side, Bernie Sanders hopes to turn his recent winning streak into concrete momentum toward the party nomination. But the Vermont senator must win 68% of the remaining delegates and uncommitted superdelegates, which would require huge victories in states both big and small, including New York.
While Mr Sanders is a Brooklyn native, Democratic front-runner Hillary Clinton is a former senator from New York, and she has been highlighting her economic record in visits to struggling cities throughout the state.
Mr Trump's remaining Republican rivals, Ted Cruz and Ohio governor John Kasich, were both in New York City on Thursday.
Former New York mayor Rudy Giuliani has announced that he will be voting for Trump in the primary.
Mr Cruz has been criticised for a comment he made in a debate in January, where he said: "Everyone understands that the values in New York City are socially liberal or pro-abortion or pro-gay marriage. Not a lot of conservatives come out of Manhattan."
The Texas senator has insisted he was not talking about the state as a whole.