Let's assume by whatever PoDs necessary, as late as possible, that:
a) The post-2008 Democratic President (who need not be Obama) and Congress majority muster a rather more aggressive Neo-Keynesian economic strategy to address the economic crisis: not so much political capital expended on the health care reform (they may address it eventually but only after they see some results about the economy), more extensive stimulus measures, bailouts to the financial sector strictly controlled, etc. They also enjoy a filibuster-proof supermajority and the President has the skills to keep the party united under his leadership.
b) Fairly soon after the sovreign debt crisis manifests in Europe, the political leaders of the Eurozone countries (who need not be the OTL figures) acknowledge the fiscal union of the Eurozone as the only effective response to the crisis, and have the determination and political leadership to successfully drive through a "grand bargain": the fiscally troubled countries accept EU supervision of their financial policy and as much austerity as it won't worsen their recession, the fiscally sound countries accept fiscal solidarity for the pooled Eurozone debt. Over a few years, the EU treaties are reformed (though the enhanced cooperation system) to implement full fiscal union for the Eurozone, managed by the Commission under the supervision of the Parliament and Council.