"We need a government that can act," Oettinger told the Deutschlandfunk radio station. "With a weak negotiating partner, there's the danger than the negotiations will turn out badly for both sides ... I expect more uncertainty now."
French Prime Minister Edouard Philippe was quick to scotch any suggestion, however, that Britain might do a U-turn and ask to stay in the EU - something that would need EU agreement - but he did expect Brexit negotiations to be "long and complex".
Germany's European affairs minister Michael Roth said that time was tight until the expiry of a two-year window to reach a negotiated deal: "We should not waste any time," he said.
But Finnish Prime Minister Juha Sipila said it looked like a possible delay in forming a new British government could hold up the start of negotiations: "The situation remains uncertain," he told broadcaster YLE. "And that is in no-one's interest."
May, who had campaigned against Brexit last year but took over the Conservative party after David Cameron lost last June's Brexit referendum, delivered her terms for withdrawal in March, setting the clock ticking on a two-year countdown to departure.
These terms include a clean break from the EU's single market and customs union. May then called a snap election hoping for a bigger majority to strengthen her hand in negotiations.
That was also the broadly desired outcome in Brussels, where leaders believed that a stronger May would be better able to cut compromise deals with the EU and resist pressure from hardline pro-Brexit factions in her party which have called for Britain to reject EU terms and, possibly, walk out without a deal.
Elmar Brok, a prominent German conservative member of the EU parliament, said Europeans would be disappointed May had failed to gain the majority that could have helped her override her party hardliners: "Now no prime minister will have that room for maneuver," he said. "Which is what makes things so difficult."
European leaders have largely given up considering the possibility that Britain might change its mind and ask to stay. Most now appear to prefer that the bloc's second-biggest economy leave smoothly and quickly. To halt the Brexit process now would require the consent of the other member states.
FEAR OF COLLAPSE
The other 27 governments are particularly concerned that a breakdown in negotiations could lead to Britain ceasing to be a member on March 30, 2019, as laid out in Article 50 of the EU treaty, without negotiating the kind of divorce terms that would avoid a chaotic legal limbo for people and businesses. That would also make it improbable that Britain could secure the rapid free trade agreement it wants with the EU after it leaves.
In a note to clients, UBS wrote that the relative strength of hardline pro-Brexit groups in a weak Conservative government could make a breakdown in talks more likely and make it harder to reach a trade deal: "A tighter political balance could make it easier for Eurosceptics ... to prevent the government from offering the compromises needed to secure a trade deal."
Talk in Britain that a different ruling coalition could seek a "softer" Brexit than May has proposed, possibly seeking to remain in the single market, is also problematic for the EU.
While the 27 would quite possibly be willing to extend to Britain the same kind of access to EU markets that they offer to Norway or Switzerland, they have made clear that that would mean Britain continuing to pay into the EU budget and obey EU rules, including on free migration across the bloc, while no longer having any say in how the Union's policies are set.
Norwegian Foreign Minister Boerge Brende said: "Maybe there won’t be a hard Brexit. Maybe Britain will have to show greater flexibility in the negotiations."
But EU leaders question how any British government could persuade voters to accept a Norway-style package and so would be wary of starting down the path of negotiating it for fear of ending up without a deal that both sides could ratify in 2019.
Siegfried Muresan, spokesman for the European center-right party whose dominant leader is German Chancellor Angela Merkel, was scathing, saying on Twitter that May had followed Cameron in risking the "future of the country for personal political gain".
She had, he said, "played with fire" in binding Britain to the two-year deadline for Brexit talks and had now "got burned".
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