But it has failed to live up to many Japanese hopes for change and analysts have said a poor performance in Sunday's elections could push Kan from office.
"Please give us not just fragile leadership but power to take action"
Kan has also seen his ratings slip in recent weeks after he floated plans to increase Japan's sales tax and failed to convince voters he had a clear plan for fixing the country's economic problems.
While he has since backtracked on talk of tax rises, Sunday's vote has come to be seen as a referendum on his leadership.
"Please give us not just fragile leadership but power to take action," he told voters recently.
"Even a great man can't make things happen in only a year. Gritting my teeth, I want to maintain power for at least five years."
The result of Sunday's election will not hit the DPJ's grip because of its control of the more powerful lower house of the Japanese parliament.
But the party needs to retain its majority in the upper house to avoid policy deadlock and begin taking steps to reduce a public debt already about twice the size of the nearly $5trn economy - the worst among advanced countries.
Surveys in several leading Japanese newspapers have forecast the DPJ would likely secure around 50 or even fewer of the 121 seats up for grabs in the 242-member upper chamber, a drop from it current 54 seats.
That would deprive the DPJ and its much smaller coalition partner, the People's New Party, of a majority and force the party to seek new allies hampering its ability to push forward the fiscal reform drive that Kan has put at the heart of his campaign.
A result of fewer than 50 seats would also leave Kan vulnerable to a leadership challenge from DPJ powerbroker Ichiro Ozawa, who has already criticised Kan's plans to raise sales tax.