Kraft Heinz Co. made a $143 billion unsolicited bid for Anglo-Dutch rival Unilever PLC, seeking to marry two of the world’s biggest packaged-food makers and accelerate an industrywide drive to cut costs amid slowing sales.

Any deal faces significant hurdles, even if Unilever management—which quickly rejected the offer Friday—ultimately comes around. The companies are big players in many of the same markets, so a combination would draw scrutiny by antitrust regulators around the world. It also could face political hurdles in the U.K. and the Netherlands, where Unilever has dual headquarters.

Unilever said the cash-and-stock offer undervalues the company. Kraft responded that it was committed “to working to reach agreement on the terms of a transaction,” though it said another offer isn’t certain.

If Kraft were to overcome these obstacles, the deal would rank as the second-largest cross-border transaction on record, behind Vodafone Group PLC’s $172 billion acquisition of Mannesmann in 1999, according to Dealogic. It would combine the No. 4 and No. 5 players in the global packaged-food industry, bringing under one roof grocery-store staples like Heinz ketchup and Ben & Jerry’s ice cream.

A deal with Unilever also would accelerate Kraft Heinz’s effort to expand in emerging markets, where Unilever generates about 60% of its sales. About 70% of Kraft Heinz’s sales come from the U.S.