TRENTON, N.J. – Republican Gov. Chris Christie on Thursday again blocked Democratic lawmakers’ attempt to have the state rejoin a regional environmental pact.

Christie vetoed a measure approved in the Legislature that would require the state to rejoin the Regional Greenhouse Gas Initiative, saying the pact is not effectively reducing greenhouse emissions. Christie pulled out of the initiative in 2011, saying it amounted to a tax on utility customers.

The state will likely rejoin the initiative after Christie leaves office in January. Democratic gubernatorial nominee Phil Murphy and Republican gubernatorial nominee Kim Guadagno both say the state should rejoin.

Nine Mid-Atlantic and New England states have agreed to cap carbon dioxide emissions and trade the excess in auctions.

“This bill is nothing more than an unnecessary, politically motivated tax increase,” Christie said in his veto message. “Pure and simple, the Legislature demonstrates its preference for higher taxes and social engineering, ignoring the overwhelming evidence proving (RGGI) to be a failure.”

Democratic Assemblyman Tim Eustace said Christie’s veto “recklessly undermines the environmentally dangerous and visible effects of pollution and climate change, some of which we have already seen in the powerfully destructive storms like Superstorm Sandy.”

States participating in the initiative are Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island and Vermont.

Christie said the state’s power sector generates clean energy in a cost-effective way while also reducing emissions.