The Blues had a trade in place that would have sent Kevin Shattenkirk to a club with a long-term extension, but the defenseman nixed the deal, the Post-Dispatch has learned.

Discussions between the Blues and another club fell apart about six weeks ago on a trade that would have given Shattenkirk a seven-year, $42 million contract ($6 million AAV), as first reported by TSN’s Bob McKenzie. League sources have independently confirmed that Shattenkirk, who is 28 and a pending unrestricted free agent, turned down the offer.

The Blues are now believed to be shopping Shattenkirk as a “rental” player, according to those sources, meaning they don’t expect him to sign a long-term deal with another club before the NHL trade deadline Wednesday. An extension elsewhere would allow the Blues to maximize his trade value, whereas being dealt as a rental will not garner the team as much in return.

The Post-Dispatch reached Jordan Neumann, Shattenkirk’s agent, Thursday night but he declined comment. Blues general manager Doug Armstrong was unavailable.

The swap of Shattenkirk would have been with an Eastern Conference team and is believed to be the Tampa Bay Lightning, with whom the Blues have long been speculated to be in trade talks.