The top U.S. Marine in the Pacific said on Friday that his forces needed to be based on the southern island of Okinawa for strategic reasons, as Tokyo struggles to resolve a dispute with Washington over relocating a base.

The relocation of the Futenma Marine base on Okinawa is at the center of a feud between Washington and Tokyo that is eroding support for Japan's governing Democratic Party and setting its coalition partners at odds ahead of an election expected in July.

Okinawa is in the perfect place in the region, said Lieutenant General Keith Stalder, when asked about suggestions that the base be moved to Guam or the tiny island of Tinian.

It's literally a day away from almost anything that can occur in the region, he said during a visit to Tokyo.

Stalder underscored the U.S. view that a 2006 agreement between the two governments to shift the Futenma base to a more remote area of Okinawa as part of a realignment that involves moving 8,000 Marines to Guam was the most desirable option.

But he said shifting all Japan-based Marines elsewhere would not be feasible.

The notion that you can have an alliance and deter and respond with only sea and air forces is a misperception that I want to dispel, he said. You've got to have ground forces.

Prime Minister Yukio Hatoyama said before toppling a long-ruling conservative party in a general election last year that the base should be moved out of the region, sparking a row that threatened to undermine ties with the United States.

The Democratic Party needs to win a majority in the upper house poll to end its reliance on an awkward coalition with two smaller parties. A poor result could even result in policy gridlock.

Media polls show concern about Hatoyama's handling of Japan's relationship with its most important ally is damaging government support.

Japanese media said on Friday the government had sounded out U.S. officials about a proposal to put a new helipad inside an existing base, but one of the Democrats' tiny allies, the Social Democratic Party, said it would be unacceptable to local people.

(Editing by Sugita Katyal)