(Reuters) – Kansas City Southern said on Thursday it has turned down a $27 billion bid from Canadian Pacific Railway and will delay a shareholder vote on a $29 billion deal to sell itself to Canadian National Railway Co if the rail regulator does not rule on the deal in the next five days.

Kansas City Southern shareholders are due to vote on the deal with Canadian National in seven days, on Aug. 19, but the Surface Transportation Board (STB) has yet to rule on the proposed “voting trust” structure of the transaction.

A voting trust insulates the acquisition target from the acquirer’s control until the STB clears the deal on a permanent basis.

The STB said earlier this week it would deliver its decision on the Canadian National deal by Aug. 31. Kansas City Southern said on Thursday that if the STB has not delivered its decision by Aug. 17, it would delay the vote so shareholders can review it. The new date for the vote will be determined later, it said.

The acquisition of Kansas City Southern by either of its Canadian peers would create the first direct railway linking Canada, the United States and Mexico.

Canadian National has said it will divest Kansas City Southern’s 70-mile (115 km) rail line between New Orleans and Baton Rouge to eliminate overlap between the two railroad operators. It has agreed to pay a $1 billion fee to Kansas City Southern should regulators shoot down their deal.

Canadian Pacific argues that Canadian National and Kansas City Southern compete for the business of shippers and terminals in the same region, which would lose out should the merger go through. It also points out that the STB has greenlighted its voting trust structure for a deal with Kansas City Southern.

Canadian Pacific presented the $27 billion offer for Kansas City Southern on Tuesday, hoping the antitrust concerns would give it an edge. It had said it would allow Kansas City Southern’s board to receive the STB decision before opining on it.

Kansas City Southern, however, took two days to review the bid with its financial and legal advisors, and said it found it not superior to the Canadian National deal.

Despite the rejection, Canadian Pacific said on Thursday it applauded the Kansas City Southern board decision to adjourn the shareholder vote absent a ruling from the STB.

Canadian National said in a statement it also supported Kansas City Southern’s decision to potentially delay the shareholder vote.

(Reporting by Arunima Kumar in Bengaluru and Greg Roumeliotis in New York; Editing by Maju Samuel and Richard Pullin)