By Rocky Swift

TOKYO, Sept 9 (Reuters) - Japan's Nikkei share average climbed past 44,000 for the first time on Tuesday as optimism over trade and potential increases in stimulus spending spread through the market.

The Nikkei 225 Index .N225 jumped 0.9% to 44,018.78 in early trading, set for a record high. The broader Topix .TOPX was up 0.4%.

U.S. tariffs on Japanese autos are set to be lowered by September 16, Japan's chief tariff negotiator Ryosei Akazawa said in an X post on Tuesday, clearing up ambiguity over a trade deal in July.

Shares continued strong gains from Monday following a resignation announcement from fiscal hawk Prime Minister Shigeru Ishiba. Sanae Takaichi, a proponent of government stimulus and monetary easing, has decided to run in the Liberal Democratic Party's leadership race, Kyodo news agency reported late on Monday, citing sources familiar with the matter.

There were 144 advancers on the Nikkei index against 77 decliners.

The largest percentage gainers in the gauge were Advantest 6857.T, up 6.7%, followed by Tokuyama 4043.T, which gained 5%.

The largest losers in the index were Citizen Watch 7762.T down 5.8%, which is set to be removed from the Nikkei in October, followed by Takeda Pharmaceutical 4502.T, which slid 2.4%.