As you'd expect, the Tories have seized on Tony Blair's declaration  that Labour must not "tack left on tax and spending". Conservative chairman Grant Shapps said:
Tony Blair is right to warn that Labour aren't a credible party of government under Ed Miliband. Ed Miliband and Ed Balls have opposed every single difficult decision this government has taken to fix the problems that Labour left behind - on welfare, on immigration and on the deficit. The only plan Labour have is more of what got us into this mess in the first place - more spending, more borrowing and more debt.
It is worth noting, however, that in his piece  Blair explicitly rejects the argument that it was overspending by Labour that "got us into this mess". While conceding that there was a case for "a tightening around 2005", Blair argues that Labour is right to be "very robust in knocking down the notion that it 'created' the crisis." As he points out, the current structural deficit was less than 1 per cent in 2007/08 and the national debt was lower than in 1997. It was the crisis that caused the deficit, not the deficit that caused the crisis.