Metro

Let 7 train go to NJ: Mike

Mayor Bloomberg wants to extend the No. 7 train into New Jersey — the first time any New York subway train would leave city limits.

The mayor’s plan would continue the subway line from its stop at 34th Street and 11th Avenue, which is still under construction, to Secaucus, NJ, where it would connect to every New Jersey Transit suburban line.

“Like others, we’re looking at — and open to discussing — creative, fiscally responsible alternatives,” Andrew Brent, a spokesman for Deputy Mayor Robert Steel, said last night.

The idea, which is still in a very preliminary stage, would be to use the partially built tunnel that would have brought Amtrak and NJ Transit trains to Penn Station before New Jersey Gov. Chris Christie killed it, citing potential cost overruns.

The feds and Port Authority had each committed $3 billion to the original project, and that money could go toward funding the No. 7 extension.

“Extending the 7 line to New Jersey could address many of the region’s transportation-capacity issues at a fraction of the original tunnel’s cost,” Brent said.

The estimated cost would be $5.3 billion — about half that of the original plan, sources said.

The West 34th Street station is slated to open in December 2013.

tom.namako@nypost.com