Rival parties were wrapping up their campaigns for local by-elections Tuesday dominated by corruption allegations and negative tactics rather than policy competition.

Voters in 21 local entities will cast ballots Wednesday to pick the new mayors of Seoul and Busan and fill other regional administrative and legislative posts.

The ruling Democratic Party (DP) and main opposition People Power Party (PPP) mounted fierce campaigns, as the elections are seen as a key barometer of voter sentiment ahead of next year's presidential election.

Opinion polls show PPP candidate as the clear favorites to win the mayoral elections in the two largest cites.

Local policy issues were largely drowned out during the 13-day official campaign period, as the DP focused on alleged real estate speculations by opposition candidates while the PPP called on voters to punish the Moon Jae-in administration for economic failures, rising home prices and graft scandals involving senior officials.

The issue of real estate was thrust to the forefront of the battle after allegations emerged in early March that employees of a public housing corporation may have used insider information to purchase land plots before they were designated for development.

The PPP used the incident to highlight the government's policy failure to curb real estate prices.

The DP raised allegations that Oh Se-hoon, the PPP candidate in Seoul, used his power to lift greenbelt restrictions on the land owned by his wife and in-laws when he was Seoul mayor in the second half of the 2000s.

The DP also charged Park Heong-joon, the PPP candidate for the Busan mayoral election, with receiving favors from a scandal-ridden developer when his family purchased luxury seaside apartment units in the port city.

Both candidates denied such claims and their opinion poll leads over their DP rivals -- Park Young-sun in Seoul and Kim Young-choon in Busan -- were not deterred by the negative campaigns.

The PPP defined the elections as a referendum on President Moon from the outset and tried to capitalize on voter disenchantment with his administration.

The party managed to forge an alliance with the minor People's Party led by Ahn Cheol-soo, a former presidential candidate, for the purpose of a change of government. The PPP's wins in the by-elections would pave the way for the merger of the two parties to challenge the DP in the March 2022 presidential election, observers said.

The PPP also highlighted the fact that the by-elections in Seoul and Busan are being conducted because of alleged sexual harassment by former mayors who were affiliated with the DP. Then Busan Mayor Oh Keo-don resigned last April and then Seoul chief Park Won-soon was found dead in an apparent suicide last July over such allegations. (Yonhap)