Qualcomm Inc. pumped new life into its bid for NXP Semiconductors NV, raising its offer to $44 billion and locking up support from key stakeholders—a move Broadcom Ltd. had warned could prompt it to end its $121 billion pursuit of Qualcomm.

The $127.50-a-share price for NXP, announced Tuesday, is the latest twist in months of maneuvering between Qualcomm and Broadcom for an advantage in what would be the largest tech deal ever.

Broadcom...