Paentongram said she was confident of winning by a landslide, with the aim of averting any political motives against her party, which previously has been removed from office by the judicial ruling and military coups.
Her support has grown by 10 points to 38.2 percent doubling the backing of her nearest contender.
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The National Institute of Development Administration (NIDA) poll of 2,000 people showed that 50 percent of respondents would choose candidates from Pheu Thai.
Incumbent Prayuth Chan-ocha has been trailing in polls and was third in the latest survey by the NIDA.
After dissolving Parliament, Prayuth told reporters he was "glad I've built something good, generated revenue for the country, built industry. There has been a lot of investment."
However, a court ruled last year that he can serve only two more years in office under the constitution.
Sources: AFP, Reuters, DW
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