They're two of the Parliament's fiercest voices on same-sex marriage.

One is a passionate advocate of marriage equality, the other a staunch defender of the status quo.

Senator Penny Wong and Senator Cory Bernardi will debate same-sex marriage on July 29. Credit:Alex Ellinghausen

Now Labor Senator Penny Wong and fellow South Australian Senator Cory Bernardi will tackle marriage reform in a debate at the National Press Club.

The pair will face-off at the end of this month before the issue is brought to a head in August with the return of Parliament and the moving of a multi-party marriage equality bill.