Japan's ruling coalition was projected to keep its majority in the upper house of parliament on Sunday, two days after the assassination of former Prime Minister Shinzo Abe, a dominant politician and power broker.

Prime Minister Fumio Kishida's Liberal Democratic Party (LDP), of which Abe was a senior figure, and its junior coalition partner Komeito were on track to win between 69 and 83 of the 125 seats contested in Sunday's vote, according to NHK exit polls.

Official results are expected on Monday.

Abe, Japan's longest-serving modern leader, was gunned down on Friday during a speech in support of a local candidate in the western city of Nara, a killing the political establishment condemned as an attack on democracy itself.

Analysts had predicted Abe's assassination might boost the LDP, led by Prime Minister Fumio Kishida, an Abe protege.

The party was projected to win 59 to 69 of the upper house seats contested, according to an exit poll, up from the 55 it held previously.

Elections for parliament's less powerful upper house are typically seen as a referendum on the sitting government. Change of government was not at stake, as that is determined by the lower house.