OMAHA, Neb. (AP) — Canadian National’s $33.6 billion deal to acquire Kansas City Southern railroad is in jeopardy. Federal regulators on Tuesday rejected a key part of the plan and opened the door for a competing $31 billion offer from Canadian Pacific Railway. The Surface Transportation Board says Canadian National won’t be able to use a voting trust to acquire Kansas City Southern and hold the railroad while the board reviews the overall deal. It wasn’t immediately clear whether Kansas City Southern will still want to move forward with CN. But Kansas City Southern is now free to accept CP’s offer, which already has regulatory approval to move forward.