Complete "Tortured Noble" at the Ar lof Denerim's estate. Talk to Irminric in the Dungeons and help him.
In the Gnawed Noble Tavern, talk to Arl Wulff and say you're sorry. Talk to Bann Sighard of the Dragon's Peak Bannorn; either ask for his support or say you don't require anything for an act of mercy. Talk to Bann Alfstanna and give her Irminric's ring; don't be too blunt with her.
If you perform the full Trial of the Crows, you gain another vote; if Alstanna and the Dragon Peak Bannorn also support you, you do not need Vaughn -nor Anora. Just make sure you choose:
1. Orlais is not the problem, the Blight is. (Bann Alfstanna back you up; so does Arl Wulff)
2. Arl Howe was allowed to torture innocents (Bann Sighard will back you up)
3. Why did Loghain send a Blood Mage to poison Arl Eamon (Bann Alfstanna backs you up and a Revered Mother -or perhaps the Grand Cleric- backs you up as well)
4. You protected Anora from Loghain (even if Anora betrays you will get enough votes to win.)