New Delhi, April 11 -- Hungarian opposition leader Peter Magyar spent most of his professional life moving comfortably within the political world built by Prime Minister Viktor Orban. Now, with pivotal elections approaching Sunday and Orban trailing in most polls, Magyar could become the former insider who brings that system down.

The 45-year-old lawyer and leader of the opposition Tisza party has charted a meteoric political rise since bursting into public view in early 2024. In just two years, he has galvanized large numbers of voters across Hungary who see him as the most credible challenger yet to Orban's 16-year grip on power.

Before emerging as the prime minister's most prominent and effective critic, Magyar spent years inside the...