Shigeru Ishiba, Japan's rapidly diminishing PM
According to media projections after elections, Ishiba's coalition was projected to have lost its majority in the upper house, a result that might push him to resign.
Late on Sunday, he was tight-lipped about his future.
"It's a difficult situation, and we have to take it very humbly and seriously," Ishiba told broadcaster NHK.
"We can't do anything until we see the final results, but we want to be very aware of our responsibility," Ishiba added.
The Liberal Democratic Party (LDP) has governed Japan almost continuously since 1955...