According to the poll data – five percent of the Israeli public supports pardoning the killer already at this point in time, while 25 percent believes that he should be pardoned in 25 years from now. Some 69 percent of respondents replied that they oppose a future pardoning. This marks a significant change compared to a similar poll conducted last year by the newspaper. Figures in 2005 showed that 76 percent of Israelis opposed any pardoning, while 18 percent believed the killer should be set free.
Among respondents defining themselves as right-wing, 54 percent support a pardoning, with 47 percent setting the pardon in 25 years. Among respondents defining themselves as religious the numbers jump again – 64 percent support a pardoning: 50 percent in 25 years and 14 percent today.
On the left only one percent of those polled believes that a pardon should be granted today. 12 percent support a pardoning in 25 years.
SourceSo first of all, it looks like you got your numbers reversed (I should note that Haaretz sees to have removed the story you linked to, and citations of the poll in haaretz - usually in opinion articles - give figures closer to the YNet account). Second, note that an overwhelming majority of the supporters of a pardon support a pardon in 25 years - something which is fairly common for prisoners serving life sentences here (there's a similiar phenomenon in Europe, AFAIK - "life" usually means two or three decades).
I think this is an inevitable result of the way the murder trial was handled. The prosecution, going by the principle of equality before the law, decided to handle the case as just a murder*, rather than the murder of a PM (IOW, the elected to ignore who the victim was). While there are things you can say in favor of that approach, it leads to the question (asked not only by the extreme right, or even the right in general) - if Amir is to be considered an ordinary murderer, isn't he entitled to the rights of ordinary murderers?
*If it had been me writing the charge sheet, I would have charged him with murder for killing Itzhak Rabin and added another charge (treason doesn't quite fit, but maybe they could make "harming the security of the state stick"**) for killing the PM (in addition to the lesser charges he was tried for, such as attempted murder (of Rabin's bodyguard).
**Of course, IANAL; possibly there was no charge that could be used like this.