TOKYO (REUTERS) - Japan's main opposition Democratic Party decided on Tuesday to back the government's nominee for the Bank of Japan governor, a lawmaker said, making it certain Haruhiko Kuroda will land the top job at the central bank later this month.

Prime Minister Shinzo Abe's government nominated last month Kuroda as BOJ governor and two other men as the BOJ deputy governors in a push for an aggressive monetary easing to rev up the economy and achieve the bank's 2 percent inflation target.

But the Democrats decided to oppose the nomination of academic Kikuo Iwata, one of the two government's nominees for the BOJ's deputy governorship, due to his radical view on monetary policy including a call to revise the law barring government's control over the central bank.

Still, the government's nomination of Iwata is likely to win approval in the opposition-controlled upper house with enough support from other fringe opposition parties in a parliamentary vote expected later this week, according to Japanese domestic media.

Prime Minister Shinzo Abe has nominated Asian Development Bank President Kuroda, an advocate of aggressive monetary easing, as the next BOJ governor, and Iwata and BOJ Executive Director Hiroshi Nakaso to be the bank's two deputy governors.

The main opposition agreed to back the nomination of Nakaso.

The nomination of the three men must be approved by both lower and upper house of parliament to take effect. If approved by parliament, the nominees will succeed incumbent Masaaki Shirakawa and his two deputies after they step down on March 19.

Prime Minister Shinzo Abe's ruling bloc controls the powerful lower house but lacks a majority in the upper chamber, thus needing the support of opposition parties to pass through the nomination.