What does Parris try to prevent in Act IV?

In Act IV of The Crucible, Reverend Parris tries to prevent the execution of the condemned, including John Proctor, Rebecca Nurse, and Martha Corey.

He specifically tries to:

* Convince Danforth to pardon the condemned. He argues that their confessions are false and that the court has gone too far.

* Discredit the accusations against the accused. He tries to convince Danforth that Abigail Williams and the other accusers are lying.

* Protect his own reputation. He fears that if the executions go ahead, he will be blamed for the witch trials.

However, his efforts are ultimately unsuccessful, and the executions proceed.