advocate / advocate for

English as a Second Language English Vocabulary, Grammar and Idioms
1

1a. They advocate abolishing the income tax.
1b. They advocate for abolishing the income tax.
2a. Those, who are the terminally ill, advocate doctor-assisted suicide.
2b. Those, who are the terminally ill, advocate for doctor-assisted suicide.
Please correct and comment.
Thanks.

2

1a. They advocate abolishing the income tax.
1b. They advocate for abolishing the income tax.
2a. Those who are terminally ill advocate doctor-assisted suicide.
2b. Those who are terminally ill advocate for doctor-assisted suicide.