BRUSSELS — The sliding euro and a downgrade of Portugal's debt put renewed pressure on European leaders Wednesday to come up with a bailout plan for Greece and stem the government debt crisis undermining their shared currency. But agreement remained elusive as a Thursday summit approached. Markets increasingly expect any bailout for Greece to involve the International Monetary Fund – and EU governments are discussing whether they would permit that and add financial help from eurozone nations. Germany is holding a back a deal, reluctant to put taxpayer money on the line for Greece.