TEHRAN "If you plan not to vote, just think about June 13 when you hear Ahmadinejad has been re-elected."
Young, urban mobile phone users in Iran are being bombarded with this and similar text messages in run-up to the poll on June 12 when hardline President Mahmoud Ahmadinejad will seek a second term.
Emails and blogs are also playing a big part for the first time in a country more used hearing political messages blared through loudspeakers on small trucks, seeing gaudy posters and being herded to campaign rallies.
The government, whose support base centers on the rural poor, is sending its own texts and emails lauding Ahmadinejad's achievements, but is also showing signs of concern.
Hardline backers of Ahmadinejad have complained about the sometimes rude jokes aimed at their leader via text messages and the official IRNA news agency said the Tehran prosecutor's office would crack down on messages offending candidates.
Popular networking and content-sharing site Facebook was shut off on May 23, joining political and human rights websites which had already been blocked.
The Facebook ban was lifted on May 26, following strong criticism from moderate candidates.
More than 150,000 Iranians are Facebook members, and young voters make up a huge bloc, which helped former reformist president Mohammad Khatami win elections in 1997 and 2001.
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Mirhossein Mousavi, Iran's prime minister during the 1980-88 war with Iraq, and former parliament speaker Mehdi Karoubi are two moderates running against Ahmadinejad along with a former head of the conservative Revolutionary Guards.
Mousavi and Karoubi see motivating young voters as key and consider texts and the web some of the best ways to do it.
One Facebook page campaigning for Mousavi, who has Khatami's backing, had more than 5,200 members.
"Vote for Mousavi and send this text to 10 others, if not you will have nightmares," an SMS message send by Mousavi's supporters reads.
Messages backing the conservative president include: "Vote for Ahmadinejad who supports the poor" and "Iranians love Ahmadinejad who preserved their dignity."
An e-mail hails the achievements of his government since taking office four years ago on a pledge to revive the values of the 1979 Islamic revolution.
"Vote for our brave President Ahmadinejad to help build a stronger Iran," it says, urging people to send it on to friends.
More than 23 million Iranians in a country of 70 million have access to the Internet. Over 45 million have mobile phones.
Many are based in cities, while Ahmadinejad's socially conservative supporters tend to live in the countryside, cut off from modern technology.
Moderates say the government wants to force Iranians to rely on sources such as state-run media, which they say favors Ahmadinejad and could put young people off voting altogether.
"We need a high turnout to win the election," said Mohammad Sedaghati, a campaigner for Karoubi.
"If Iranians boycott the election, we will lose to Ahmadinejad whose supporters will surely vote."
(Editing by Philippa Fletcher)