A recent bill put to the vote in the US Senate that would have introduced tax incentives for LNG fueled vehicles failed by a vote of 51 for and 47 against. 60 votes were required beause the legislation was drafted as an addition to the Senate's highway bill. Supporters of the bill still feel optimistic about the industry's ability to push forward despite the failure to secure these incentives.
The legislation's tax incentives were designed to help the transition of long haul trucks from fuel based on foreign oil to natural gas which the US has in abundant supply. The arguments for the bill are to reduce America's dependence on foreign oil and to encourage growth of our own natural gas infrastructure. Opponents of the bill say that it interferes with free markets, giving one industry the advantage over another.
Further sources of reading: