Someone needs to go the Prime Minister, place his/her left hand on the PM's shoulder, look into into his eyes and tell him:
"You know the loss of seats in the House of Councillors' election? It was not your fault. The presence of Minna no To candidates in the districts cost the Democratic Party between five and eight seats. Cooperation between the New Komeito and Liberal Democratic Party -- cooperation that was almost certainly the result of threats that Ozawa Ichiro has been making for years against the numbers of proportional seats in the Diet -- cost the DPJ probably at least another four seats. The reason why Minna no To represented an attractive non-DPJ, anti-LDP alternative in the proportional vote? The accounting crimes of former Prime Minister Hatoyama Yukio's aides and the media pogrom against a single Ozawa real estate deal. That and Hatoyama's inability to take a stand upon anything during his brief tenure.
You need to stop blaming yourself for what happened. You always go overboard in taking responsibility for matters that an objective third party would declare to have been outside your control. As regards the consumption tax you said something tactically stupid but strategically wise.
Laugh off the loss and start cracking the whip.
Oh, and another thing - the Finance Ministry bureaucrats you and Chief Cabinet Secretary Sengoku Yoshito have been relying upon as Japan's ultimate realists? Think of them as Japan's Taliban. Sure it is an unfair and outrageous depiction, but you need an extra strong aversion to their seeming mastery of the numbers. Otherwise you will not lead, you will be led. Minus a visceral negative mindset you will fail to resist their depressed and depressing certitude."