Donald Trump canceled a planned trip to California, including a press conference at the Trump National Golf Club Los Angeles in Rancho Palos Verdes that had been scheduled for Friday.
The announcement comes as the candidate refocuses his efforts on his home state of New York. Trump has been solidly ahead in polls in New York, while he faces a closer contest in California, though the latest Field Poll shows him ahead of Ted Cruz.
Trump is also expanding veteran operative Paul Manafort's role in his campaign amid the increasingly likelihood of a contested Republican convention.
The campaign said in a statement Thursday that Trump is "consolidating the functions related to the nomination process" and assigning them to Manafort, who last week was named convention manager.
The statement stresses he will be "working closely" with Trump's existing team, including campaign manager Corey Lewandowski.
But it said Manafort "will oversee, manage, and be responsible for all activities that pertain to Mr. Trump's delegate process and the Cleveland Convention."