The visitors led on 33 minutes when Fitz Hall failed to clear Hulse's cross, allowing Blake to tap in.
And they made it 2-0 after the break when Hulse diverted Liam Miller's cross in off the bar.
Palace improved after Aki Riihilahti's introduction but Jobi McAnuff's curling 20-yard effort was only a consolation.
Leeds boss Kevin Blackwell:
"People thought the race for automatic promotion was finished a long time ago, but we never agreed.
"Sheffield United are still in the ascendancy, but we feel we have a chance of catching them.
"We have to keep chasing, and we are doing as much as we can."
Crystal Palace: Kiraly, Ward, Fitz Hall, Boyce, Borrowdale, McAnuff, Watson (Riihilahti 56), Hughes, Soares (Leigertwood 58), Johnson, Morrison.
Subs Not Used: Popovic, Andrews, Speroni.
Goals: McAnuff 90.
Leeds: Sullivan, Kelly, Crainey, Butler, Gregan, Lewis (Pugh 87), Miller, Douglas, Derry, Hulse, Blake (Healy 87).
Subs Not Used: Bennett, Bakke, Moore.
Goals: Blake 33, Hulse 53.
Att: 23,843
Ref: D Gallagher (Oxfordshire).