TOKYO — A battle between rival blocs in Japan’s ruling party escalated Monday ahead of a tax hike vote that is threatening to split the party and weaken Prime Minister Yoshihiko Noda’s hold on power. The legislation expected to come before parliament Tuesday includes a doubling of the current 5 percent sales tax. Noda says it is needed to fight Japan’s swelling national debt, but the political maneuvering has overshadowed economic debate on the bill. Media reports Monday said more than 50 ruling party lawmakers plan to vote against it. That would not be enough to kill the bill, because it also has opposition party backing. But the reports also said dozens of lawmakers are considering leaving the ruling party altogether in protest. — AP