The tax table being discussed is on 2009 earnings and those will be settled in 13 months. The tax table itself was passed in 2008 as part of an omnibus tax bill. Two things can happen 1) in this year’s tax bill the Congress can include an adjusted tax rate or put in a deduction as in prior years. 2) There may be a rebate passed.
The president of the United States does not pass laws, the Congress does as every native citizen would know if s/he paid attention in Civics class. The president may make requests but a Democratic Congress will do what they want. All this takes time.
A bill must be written then introduced into the House it then goes to committee and hearings are held and an amended version is sent back for debate by the full House and other changes might be made. Then it goes to the Senate where again there may be committee hearings and debate. Finally both versions go to a joint committee where they come up with a final bill to send to the president, At any point a bill could be delayed by the opposition. As you can imagine this process can take many weeks.