you should ask yourself why Obama's approval ratings are actually very strong, and steady (especially compared with Reagan and Clinton at this point in their first terms) when considering a 9.8% unemployment rate.
Obama does have a grace period, but its not going to last forever. His approval ratings have been as low as 41% over the past few months which is not good regardless of the situation or comparisons to past Presidents. Obama's monthly average on approval will continue to decline the longer the unemployment rate remains so high.
you also need to look at the fact that when Obama took office the economy was shedding jobs, now it is adding jobs. the economy is fundamentally better now than it was at the end of 2008. it's not a comparison of 2000 vs. 2012, or 2004 vs. 2012. yes, the unemployment rate is much higher than it was under Bush, but Bush's continued abysmal approval ratings (and the fact that no Republican will go near him) demonstrates that most voters actually do place blame for the unemployment rate with him rather than with Obama.
In February of 2008, Bush's last year in office, the unemployment rate was only 4.8%. Its true that in Bush's last 6 months in office the unemployment rate suddenly and steadily climbed. When Obama came in, in January, unemployment was about 7.5%. But after Obama was in, it climbed as high as 10.1%, is currently at 9.8% and is not really moving much.
Its not enough that jobs are being added. You have to add jobs every month just to keep up with new people entering the work force. Its not enough to have some GDP growth and some job growth. Voters won't feel that.
What voters do feel is the most difficult job market since the 1930s. A jobs situation that worsened for months after Obama entered office and has not noticably improved for the voters. Obama still has time to try and change the situation, but time is running out. Obama cannot run against George Bush in 2012. He can't really run against Republicans in 2012 since they only control the house. He is going to be on the defensive and will have to explain to voters why he deserves another term. Sustained unemployment rates above 9% are not going to increase voter appreciation. People are going to start to look elsewhere when the campaign starts if the situation continues.
now, whether or not Obama has done enough to fix it is the question, not whether or not he is the cause of the 9.8% unemployment.
Well, not all voters look at it that way. Many will remember what life was like four years ago and simply conclude that Obama has done a poor job. The fact is, whether he is at fault or not, the overwhelming majority of the high monthly unemployment rates have happened under Obama. If that persist, that is what people will remember and think about on election day. No one is going to remember that the economy started to deteriate in the last 6 months when Bush was President. They are going to be focused on four years of unemployment above 8% or 9% under Obama, consistantly, month after month, which is something the country has not seen since the 1930s.
Even people that generally like Obama will be attracted to someone new, something different, in order to bring about some sort of change in the jobs situation.
Bottom line, there has to be significant improvement in the jobs situation for voters in order for Obama to have a decent chance at re-election. The next 8 months is very important.