TOKYO, July 21 (Xinhua) -- Japan's ruling coalition led by Prime Minister Shinzo Abe is set to win more than half of the contested seats in Sunday's upper house election, maintaining a majority in the chamber, according to Kyodo News and NHK exit polls.

According to the polls, the ruling bloc is expected to win at least 63 out of the 124 seats up for grabs, crossing the victory line set by Abe to maintain a majority in the 245-seat chamber.

Meanwhile, the ruling parties and others who advocate constitutional reform are possibly picking up 86 seats to get a two-thirds majority, NHK reported.

Abe will need such a majority in both upper and lower houses to hold a national referendum on a constitutional amendment.