NEW YORK - Talks are now being revived about extending the 7 train under the Hudson River to New Jersey.

The idea was first floated in 2010 by then mayor Mike Bloomberg, when the 7 line was being extended to Hudson Yards on the far west side of Manhattan. 

Now it's being considering again as the Port Authority studies commuter rail options between New York and New Jersey.

But critics say the transit system has more pressing needs.

"At this moment, both the Port Authority and New York City Transit have major other projects. It's not the time to be thinking about this kind of expansion. The NYC Transit really needs to focus on fixing the subway system. New Yorkers can tell you that the system is not nearly as reliable as it should be," said Tabitha Decker of the Transit Center.

It's not clear how much a New Jersey extension of the 7 would cost.

The city paid $2.4 billion to extend the line one mile from Times Square to Hudson Yards.