Russia's new president arrives in Berlin Thursday for his first official visit to the West.
Opposition to Ukraine and Georgia's US-backed membership bids, led by Germany, is widely seen as an effort to preserve Europe's growing energy ties with Moscow.
A consensus to isolate the group is fraying due to the lack of political results.
Gazprom rattled the European Union by cutting – then restoring –Ukraine's gas supply this week.
Secretary of State Rice arrives in London Wednesday to address tensions among key allies.
Presidential polls take place Sunday amid intense debate that has pitted hard-line nationalists against more moderate politicians.