BUDAPEST, April 1 (Reuters) - Hungary's centre-right Tisza party widened its lead over Prime Minister Viktor Orban's ruling Fidesz ahead of an April 12 parliamentary election, two opinion polls showed on Wednesday, although a large share of voters remained undecided.
Veteran nationalist Orban faces the biggest challenge to his rule in 16 years, although the outcome of the election remains uncertain uncertain due to the many undecided voters, according to opinion polls.
Centre-right Tisza, led by former government insider Peter Magyar, had the support of 56% of decided voters, up from 53% in early March, while 37% backed Fidesz, down from 39% three weeks ago, a poll by 21 Research Centre showed.
Some 26% of respondents did not know who to back.
The poll, conducted between March 23 and 28 with a sample size of 1,500, showed Tisza leading Fidesz by 19 percentage points, up from a 14-point lead in the earlier poll.
Published by news site 24.hu, the survey showed 40% support for Tisza among all voters, with Fidesz backed by 28%.
ONE-FIFTH UNDECIDED IN SECOND POLL
Another poll, published Tuesday and conducted by Zavecz Research, showed that Tisza widened its lead to 13 points among decided voters from 12 points in a February poll.
Conducted between March 24 and 28, the poll showed 51% of voters supported Tisza, up from 50% in February, while 38% backed Fidesz, unchanged from a month earlier.
Zavecz showed 39% support for Tisza among all voters, while Fidesz was backed by 31%. They said that 20% of respondents were undecided, and the survey had a sample size of 1,000 people.
Magyar has said his Tisza party would curb corruption, unlock billions of euros in frozen European Union funds to boost the economy, and firmly anchor Hungary in the EU and NATO.
While most polls have shown a Tisza lead, Fidesz points to other surveys that still show it on course to victory, though its opponents say these have mainly been conducted by institutes with financial or personal ties to the ruling party.
21 Research Centre and Zavech Research are both independent of political parties and gathered responses by phone calls and online questionnaires.
Both surveys showed that the far-right Our Homeland (Mi Hazank) could be the only other party to pass the 5% threshold required for entry into parliament.
21 Research Centre put support for Our Homeland at 5% among decided voters, and Zavecz at 4%.
(Reporting by Anita KomuvesEditing by Bernadette Baum)
