Umbridge

[catherine higgins]

No: HPFGUIDX 147752

    
April responds:

So, what was the actual reason given
for the dementors?  Did they just want him expelled??

Catherine:
  Umbridge (and the rest of the MoM) want Harry discredited.
 They want him to look like a big show-off, an attention seeking brat. 
A kid who would do anything to stay in the limelight. 

Umbridge says it herself (OOP, ch 32 p.658 UK edition 
I think since I'm in Canada...) 
Harry: "you sent the Dementors after me?" 
   
  "Somebody has to act," breathed Umbridge, 
as her wand came to rest pointing dirsctly at Harry's forhead. 
"They were all bleating about silencing you somehow -
 discrediting you - 
but I was the one who actually did something about it...
only you wriggled out of that one, didn't you, Potter?"...

Catherine