SAN JOSE (Reuters) - A conservative Christian congressman best known for his opposition to gay rights remains the favorite in Costa Rica’s presidential election next month, according to a poll released Tuesday night.

FILE PHOTO - Fabricio Alvarado, presidential candidate of the National Restoration party (PRN), reacts in a car during his visit to a neighbourhood in San Jose, Costa Rica, January 27, 2018. REUTERS/Juan Carlos Ulate

Fabricio Alvarado, a 43-year-old ex-television host and the only lawmaker from the evangelical National Restoration party, led in several run-off scenarios in the Jan. 29-30 survey conducted by OPol Consultores.

Election experts say a second round run-off is likely as no candidate is expected to win at least 40 percent of the vote in the Feb. 4 election.

A run-off featuring the top two vote-getters would take place in early April.

In a hypothetical match-up against Antonio Alvarez of the National Liberation Party (PLN), Alvarado would win with 37 percent support compared to Alvarez’s 34 percent, according to the poll.

The OPol Consultores poll has a margin of error of 3.3 percent.

Alvarado has even larger leads in potential run-offs with other candidates, including conservative lawyer Juan Diego Castro of the small National Integration Party (PIN) and Carlos Alvarado, the candidate from President Luis Guillermo Solis’ ruling Citizens’ Action Party (PAC).

Alvarado gained momentum in the race after he expressed his strong opposition to a January ruling by the Inter-American Court of Human Rights, which called for the legalization of same-sex marriage.

Costa Rica is one of the more prosperous and stable countries in Central America. It had been ruled by a two-party dynasty until an upset in the 2014 vote that brought to power Solis, a center-left academic who had never held elected office.

Under Costa Rican law, Solis is barred from seeking immediate re-election.