Answer
Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Responding to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Jumu`ah khutbah is not intended to be a political sermon; rather it is primarily meant to inspire people spiritually and remind them of Allah, remembrance of death and standing before Allah for judgment.
So by devoting the khutbah to deal with the political issues, he is distracting people from the remembrance of Allah. He may do well to read the khutbas of the Prophet and the pious caliphs; however, the problem Muslims often face is that we have no shortage of people who perform such duties without proper training.
So, in these circumstances, you are justified in going to another mosque where you will not be distracted by such sermons.
Allah says: O you who believe when the call to Prayer is sounded on Friday, hasten to the remembrance of Allah, leaving behind you all other business; and remember Allah much so that you may succeed.”
According to eminent scholars, khutbah is meant to be a means of establishing remembrance of Allah. How can it be so when the preacher is giving a political lecture or speech.
Furthermore, khutbas should not exceed more than 20 minutes. The Prophet (peace be upon him) as his beloved wife Aishah tells us never gave lengthy sermons: rather his speeches were always and to the point so that at the end of the address people could retain the essential message and uplift themselves spiritually.