SCENARIOS: What to expect from the G20 Summit

LONDON (Reuters) - G20 leaders from top industrialized and emerging economies are meeting to chart a path to recovery from the world's worst economic crisis since the 1930s.

They will seek to agree at a G20 summit on Thursday what fiscal and monetary measures are needed to restore growth, what regulatory changes are needed to the financial system and how to reform international forums such as the International Monetary Fund.

Wary of the threat to confidence any overt disagreements would pose, G20 leaders are under pressure to show a united front at the summit hosted by Prime Minister Gordon Brown.

But cracks have shown among policymakers -- particularly over support packages and regulation. Below is a look at what the G20 can realistically hope to achieve.

FISCAL AND MONETARY STIMULUS

Best outcome for summit: A strongly-worded commitment to raise spending and do whatever it takes, in a co-ordinated manner, to get the global economy back on track. No public bickering between nations on the best way forward.

Most likely outcome: A firm commitment to act as necessary to restore growth. Criticism already has started from France and Germany of excessive public spending plans.

Where the G20 stand:

Draft Communique: No new commitments, beyond saying "we are committed to deliver the scale of sustained effort necessary to restore growth while ensuring long-run fiscal sustainability." And on financial institutions: "We are committed to take all necessary actions to restore the flow of credit."