I seriously doubt Bush jumped 5% anywhere - the journalists who use a criteria of 50% at this stage are not basing it on any analysis but just the view that you need 50% plus to win. This not only assumes that you get none of the unsure - it doesn't take into to consideration that elections are constrained choices.
This bothered me seeing people overjoyed with Bush anywhere from 45 to the low 50s depending on the polls. The problem is that the nos included both the "Pat Buchanans" who given Kerry or Bush would still vote Bush. Also it would seem that the people who approve are more likely to vote than the disapproves who may or may not be motivated enough by the alternative. Kerry is also likely being "punished" by HRC people who are saying no - though I assume they will still vote for him.
Here Kerry is at 49, but he will get the Democratic nomination - and we just saw the polls that put him double digits ahead of both Republicans. The real problem is getting people to see what he has done. I am still shocked that other than KERRYVISION which is beyond outstanding I haven't seen anything about two different Bush administration people giving Kerry extraordinary praise for helping in Bali - I put the links and quotes in Whometense's thread. I would imagine that quoting from a committee hearing is allowed and that most of MA would see that being in on the treaty is better than letting things fall apart - and you have a Bush guy saying that without Kerry it wouldn't happen.
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=273x148172#148248