PHNOM PENH, Cambodia (AP) — Cambodia's national election body on Monday rejected a late bid by the country's opposition leader to register as a candidate and vote in the general election this coming weekend.

The National Election Committee said in a letter to Sam Rainsy, head of the Cambodia National Rescue Party, that he had missed the deadlines for both running and voting in the July 28 polls. Rainsy and his lawyers had applied for him to vote and be on the ballot.

Prime Minister Hun Sen's Cambodian People's Party is expected to maintain its large majority in parliament, but the vast and enthusiastic crowds that greeted Rainsy's return on Friday suggest the opposition may make its strongest showing ever.

Rainsy returned from self-imposed exile last week after archrival Hun Sen arranged to pardon him for convictions that would have put him in prison for 11 years. Rainsy had called his convictions politically inspired.

Hun Sen has been in power for 28 years and says he has no intention of stepping down soon. His authoritarian rule has given him a stranglehold over the state bureaucracy that makes challenges to his authority difficult to mount.

Rainsy and Cambodian and international rights groups charge the election environment and preparations do not meet international standards for being free and fair, with Hun Sen and his ruling party maintaining too much influence over the process.

Hun Sen said he sought the royal pardon from King Norodom Sihamoni in the interests of national reconciliation and unity. However, the move is more generally seen as an effort to undercut criticism over the polls, which had focused on Rainsy's exclusion. The U.S. and other governments had said Rainsy's exclusion from the campaign would call into question the polls' legitimacy.

The ruling by the National Election Committee is unlikely to slow the momentum of the opposition's new upsurge as Sam Rainsy, a charismatic and fiery speaker, attracts large crowds on a whirlwind schedule taking him to over a dozen provinces in a week.

In the long run, however, it puts him in a legally vulnerable position, as he will not have the protection of parliamentary immunity from arrest. In recent years, Hun Sen and his ruling party, who used to be accused of the widespread use of violence and intimidation against their opponents, have instead used the courts to harass and cripple them. The judiciary especially is criticized by rights groups for being under the government's influence.

Hun Sen has ruled Cambodia for 28 years, and his party has 90 of the 123 seats in the National Assembly. The 60-year-old prime minister recently said that he intends to stay in office until he is 74 — cutting back from an earlier vow to stay in control until he's 90.

The election will be the fifth parliamentary poll since the United Nations brokered a peace deal for Cambodia in 1991, a process mean to end the decades of bloodshed that included the communist Khmer Rouge's catastrophe 1975-79 rule, during which an estimated 1.7 people died in torture centers and labor camps or of starvation or disease.