U.S. railway operator Kansas City Southern (KSU.N) said on Thursday that it had accepted Canadian National Railway Co"s (CNR.TO) $33.6 billion acquisition offer, upending a $29 billion deal with its competitor Canadian Pacific Railway Ltd (CP.TO). The development, first reported by Reuters, gives Canadian Pacific five business days to make a new offer for Kansas City Southern. Were Canadian Pacific to table a new offer, a bidding war could ensue. Canadian Pacific had previously announced a deal to buy Kansas City Southern on March 21, before Canadian National said it had submitted a higher bid on April 20. The headline price in Canadian National"s cash-and-stock bid remains $325 per share as originally announced, though the company offered more of its shares to compensate for a decline in its stock price. Canadian National has offered to cover the $700 million break-up fee Kansas City Southern will owe Canadian Pacific Railway Ltd (CP.TO). It will also pay Kansas City Southern $1 billion if the U.S. Surface Transportation Board (STB) rejects a voting trust structure it has put forward to complete the deal. "We believe that Canadian Pacific"s negotiated agreement with Kansas City is the only true end-to-end Class I combination that is in the best interests of North American shippers and communities," a Canadian Pacific spokeswoman said. Canadian Pacific and larger rival Canadian National are in a race to take over the U.S. railroad operator, which would create the first direct railway linking Canada, the United States, and Mexico. Either of them acquiring Kansas City Southern would create a North American railway spanning the United States, Mexico and Canada, as supply chains recover from COVID-19 pandemic-led disruptions. The acquisition interest in Kansas City Southern also follows the ratification of the U.S.-Mexico-Canada Agreement last year that removed the threat of trade tensions, which had escalated under former U.S. President Donald Trump. The STB last week approved the voting trust for Canadian Pacific"s proposed acquisition. Canadian National has offered an identical arrangement. read more