The man accused of attacking US House Speaker Nancy Pelosi's husband has told police he was planning to knee-cap her, in what authorities are calling "politically motivated" violence.

David DePape has been charged with a range of state and federal offences, including attempted murder. With a week to go before the US midterm elections, calls are growing for lawmakers to address growing political polarisation and the online misinformation that fuels it. 

USSC non-resident senior fellow Bruce Wolpe spoke to ABC's PM about the latest news.