DEBRECEN, Hungary (AP) — A rising challenger to Hungarian Prime Minister Viktor Orbán held what he called the largest countryside political demonstration in the country’s recent history on Sunday, the latest stop on his campaign tour that has mobilized thousands across Hungary’s rural heartland.

Some 10,000 people gathered in Debrecen, Hungary’s second-largest city, in support of Péter Magyar, a political newcomer who in less than three months has shot to prominence on pledges to bring an end to problems like official corruption and a declining quality of life in the Central European country.

Supporters endured a brief but unexpected rain shower ahead of the afternoon demonstration, turning the city’s central square into a sea of umbrellas. They waved Hungarian flags bearing the names of towns and villages across the country from which they had come.