By Omer Esiner of TravelexThe dollar firmed against most of its major rivals overnight as continued concerns about Greece's debt crisis weighed on the euro and undermined investors' appetite for risk. Wrangling among eurozone officials continues to highlight the lack of cohesion within the bloc and raises the risk that policymakers will not be able to reach an internal solution to Greece's debt woes at this week's summit of EU leaders. Such a scenario could result in Athens seeking assistance from the IMF. Uncertainty ahead of the summit, scheduled for Thursday and Friday, has kept the single currency under pressure and dampened some demand for riskier assets like commodities and emerging market currencies. Sterling resumed its decline overnight after consumer inflation data undershot market expectations. The data suggested that inflation in the U.K. may have peaked over the near term and brought back into the spotlight the long list of headwinds facing Britain's economy and the pound. EUR: The euro fell back toward a three-week low against the greenback and a 30-month trough against the Canadian dollar, broadly undermined by uncertainty ahead of this week's summit of EU leaders. German Chancellor Angela Merkel, who faces intense domestic opposition to any assistance to Greece, continues to say that a bailout for Athens is not even to be a topic of discussion at the summit. Merkel faces an election later this year. Her position prompted European Commission President Manuel Barroso, to call on her to "rise above domestic politics" to avoid risking more damage to the euro. Greek officials meanwhile, continue to threaten to seek IMF assistance if an internal eurozone resolution is not reached this week. All the bickering has highlighted the lack of cohesion within the bloc and has raised questions about the viability of a monetary union without political unity. Investors have pushed the single currency roughly 10% lower against the dollar in 2010 and are likely to continue to penalize the euro in coming months. Even in the unlikely event that Europe's debt issues fade, the fiscal tightening needed to get budget deficits down will undermine already weak growth and keep the ECB sidelined longer than other major central banks.