The bouquets for Suu Kyi hide the challenges for her budding NLD party

Myanmar's pro-democracy leader Aung San Suu Kyi waves to her supporters during an election rally on March 10.

MAWLAMYAING, MYANMAR // Cho Cho May knows who she will vote for in next month's Myanmar by-elections: the candidate for the party created by the former military junta.

"No need to ask me that question," she says. The Union Solidarity and Development Party (USDP) candidate is her boss.

Finding another USDP supporter elsewhere in this normally sleepy river town is harder.

When Aung San Suu Kyi, who leads the rival National League for Democracy (NLD), is on a two-day campaign tour of the region, Mawlamyaing's streets throng with people waving NLD flags and shouting "Long live Mother Suu!" Watch Ms Suu Kyi's huge convoy go past - it includes a lorry just to carry the flowers that people give her - and you wonder how anyone could beat her party at the polls.

But the NLD, which is fielding candidates in all but one of the 48 seats contested on April 1, faces a number of challenges. These include candidates with low recognition, an inexperienced and still-fearful electorate and a well-funded incumbent whom the NLD alleges is playing dirty.

After decades of military dictatorship, a nominally civilian government last year embarked on a series of dramatic reforms. It has released political prisoners, including Ms Suu Kyi, relaxed media controls and vowed to tackle its dysfunctional economy.

The April 1 poll is the first big test of Myanmar's electoral probity and the popularity of Ms Suu Kyi's rejuvenated party.

The United States and European Union regard free and fair by-elections as a crucial condition for dismantling years of economic and political sanctions against Myanmar.

The current government took power after a 2010 general election that was boycotted by the NLD and widely criticised as rigged.

With just three weeks left till the polls open, the NLD is already crying foul. It has accused the government of hampering its populist campaigning by a sudden ban on the use of sports grounds for political rallies.

Suu Kyi's latest rally on Sunday was held not in Mawlamyaing, but on a scorched field set amid a rubber plantation about 10 kilometres from town. The five-thousand-strong crowd arrived on a fleet of lorries, buses and motorbikes.

Ms Suu Kyi has complained of "huge errors" in official lists of voters, which omitted or repeated names, or included those of dead people. In a March 6 stump speech, she railed against political parties that try to "win parliamentary seats by dishonest means" and said that NLD campaign posters in the capital Naypyitaw had been vandalised.

President Thein Sein's administration seems torn between avoiding actions that could potentially derail the lifting of sanctions, and reverting to old ways.

Like all political parties contesting the by-elections, the NLD is allowed to record a 15-minute campaign speech to be shown twice on state-owned MRTV. The text must be submitted in advance to be approved by the information ministry.

One paragraph in Ms Suu Kyi's speech, in which she criticised past military governments for "oppressing the people," was cut out, she told the Myanmar-language service of Radio Free Asia on Friday.

"Aung San Suu Kyi is the right person for the country, but behind her is not much," says Khin Shwe, a USDP lawmaker and real-estate tycoon with close ties to the former junta. "But the USDP has already chosen the right people for many seats. After Aung San Suu Kyi, the NLD has to choose the right people."

He insists the vote will be free and fair but expects the Ms Suu Kyi's party to win only half the contested seats. "I think it will be 50-50."

The NLD's high-energy campaign contrasts sharply with the torpor at the USDP headquarters.

"There is no need for the USDP to campaign," says the independent economist Khin Maung Nyo. "Even if the NLD win all 48 seats, it is negligible. But I think there will be a big struggle between the NLD and the USDP in the next [general] election in 2015."