Campaigning kicks off Tuesday for three Lower House by-elections set for April 28, with the results likely to determine whether Prime Minister Fumio Kishida’s position within his party is strengthened or weakened.

On the one hand, Kishida might be pleased that his Cabinet support rate increased by 5.4 percentage points, to 26.3%, in a TV Asahi poll conducted over the weekend, as the prime minister returned from a state visit to the United States. On the other hand, in the same poll, 81% criticized him over his handling of the political slush funds scandal that has rocked his ruling Liberal Democratic Party.

In two of the upcoming races — those in Nagasaki Prefecture and Tokyo — the LDP is not fielding candidates. So it's the third contest in Shimane Prefecture — where an LDP candidate is facing a Constitutional Democratic Party candidate — that is seen as a must-win for the ruling party.