The ruling Liberal Democratic Party has gained a lead over opposition forces in 22 out of the country's 32 single-seat constituencies ahead of Sunday's Upper House election, the latest Kyodo News poll shows.

In the prefectural-based districts where only one seat is up for grabs, opposition parties have joined hands to field single candidates to face off with their LDP rivals in the hope of avoiding splitting the anti-LDP vote.

But the opposition has an edge in only Okinawa and Nagano prefectures while running neck-and-neck with the LDP in eight other districts, according to the three-day telephone survey conducted through Tuesday as well as an analysis of information gathered by Kyodo News.