WI: The Confederate Navy held Mobile Bay

During the first week of August 1864 Federal forces lead by Rear-Admiral David Farrugut assaulted the Confederate Naval forces at Mobile Bay commanded by Admiral Franklin Buchanan. Mobile bay was important for being the last major Confederate port in the Gulf of Mexico. The loss of its capture by Union cut off the supply line from it the lead to the ANV and some believe that its capture along with that of Atlanta's helped Lincoln win his reelection.

IOTL all the people involved said that it was a hard earned victory. So with the high chance of failure that the Union faced I'd like to ask what kinds of outcomes could be expected if they had not captured Mobile Bay and allowed it to stay under Confederate control. What battle plans would the Union have changed if they hadn't had Mobile Bay? Would Lincoln have still been reelected? What changes made by the Confederates to their war plans after the bay's loss in OTL might be avoided? What other butterflies could occur?
The continued presence of a Union Army force near Mobile would've kept the pressure up on the defensive forts manned by the Confederates even if the US naval contingent was unable to win a victory by sea.
Thanks, could you give me any more ideas about what could happen, and what some far reaching butterflies could be?
Actually not much changes. If the initial attempt fails the Union will simply try again later. Meanwhile the troops will still be landed, the forts will still be bombarded, and the blockade will still be maintained. At best the forts and Mobile will hold out for a few weeks longer than OTL, but the eventual outcome will be the same.