The latest failure of Republicans to pass healthcare legislation in the United States was also playing in to the dollar's weakness, further undermining faith in President Donald Trump's promises of other measures to support growth.
Eyes will again be fixed on the central banking conference in Sintra, Portugal, with several ECB officials speaking, along with Bank of Canada Governor Stephen Poloz and the Bank of England's Mark Carney.
The dollar's weakness pushed sterling, again under pressure from Britain's recently volatile politics, above $1.28 to its highest since Prime Minister Theresa May lost her parliamentary majority on June 8.
Conversely, it hit its weakest since November at 88.79 pence per euro.
"No matter the subtlety of any shift in guidance (by Draghi), the reaction in a yield-sensitive market is generally binary and we may well have to add currency appreciation to the risks facing ECB policy," said Bank of New York Mellon strategist Neil Mellor.
"Euro bulls may now feel that they have the perfect opportunity to challenge the post-2015 trading range whose ceiling is a couple of big figures north of spot."