The 2020 European Championship will be played across the continent, giving about 45 countries hope of hosting the soccer showcase.
A decision on how many cities and countries will stage the 24-team, 51-match tournament is scheduled for the spring of 2014.
Gianni Infantino, general secretary of European soccer's governing body, called the format a "Euro for Europe" and the fulfillment of a wish by UEFA President Michel Platini, who floated the idea in June.
"The only thing that is decided is that the concept is changing. This leaves the door open to all countries," said Infantino, adding that 52 of UEFA's 53 national members gave support in recent consultations.
UEFA's executive committee committed to Platini's project despite opposition from his most senior vice president, Senes Erzik of Turkey. He wanted his country to host the tournament alone.
UEFA said the multinational hosting plan is in place only for Euro 2020, and the 2024 host will be chosen in a traditional bidding contest.
Platini wants to ease the cost burden on hosts and fans, and give smaller countries an opportunity to be in the sport's global spotlight.
The former France star said he was "really passionate" about the plan during Euro 2012, after seeing how co-hosts Poland and Ukraine had been stretched to finance and complete stadiums, airports and infrastructure costing billions of dollars for just 16 teams.
France will be the sole host for an expanded 24-team tournament in 2016, having edged Turkey in a final vote.
UEFA believes the financial demands are too much for one or two hosts during a prolonged economic downturn.
"The economic situation is such that you can't expect countries to invest in sporting facilities that such an event requires," Infantino said. "The fact that the Euro moves from 16 to 24 teams bears an additional burden on a country to host the event."
Infantino suggested that the tournament could allow fans in "10, 12, 15" countries to cheer their teams in matches played at home.
The detailed task of suggesting a format and logistics for the monthlong tournament will be studied by UEFA's national team competitions panel.
Infantino hinted that smaller countries that have never hosted a Euro, World Cup or Champions League final could be encouraged in a yearlong bidding process that will begin in January or March.
Romania, which hosted the Europa League final in May at a new, 50,000-plus stadium in Bucharest, will be a strong candidate to host up to four matches.
Countries such as Hungary, Cyprus or Estonia could be given an "impetus to build such a national stadium" seating about 40,000, Infantino suggested
"We hope we can boost national team football with this decision," he said.
Still, major European powers such as England, France, Germany, Italy and Spain will expect to be included. Some UEFA members, whose entire population could fit in such a venue, can be excluded from calculations.
One model format for Euro 2020 has each of the six four-team groups allocated to two cities. Those 12 total venues could then get one match each — completing an allocation of four — in the last 16 and quarterfinals stages combined. A 13th host could then stage the semifinals and final.
Domenti Sichinava, president of Georgia's soccer federation, told The Associated Press on Wednesday that his country could share group hosting with Azerbaijan, Belarus, Russia or Turkey.
England has expressed interest in hosting the final stages at Wembley Stadium. Istanbul is another contender after Turkey was overlooked as the perceived favorite for sole rights to Euro 2020.
The UEFA panel advising on possible formats must look at how many countries could want, or expect, home advantage to create a festive atmosphere.
Infantino said fans would find it "difficult to understand" if their country was a host but its national team played elsewhere.
The hosts, however, must be chosen "well in advance" of the qualifying matches. Qualifiers would likely be completed up to eight months before the first Euro 2020 match.
"This will have to be thought about," Infantino acknowledged.