How Democrats stole US Congress from Trump

Donald Trump's Republican Party has lost control of both houses of Congress at the US midterms, with Democrats flipping Senate seats in Texas, Ohio, Kansas, Iowa, Maine and the Carolinas.
A US politics expert from the University of Sydney says widespread disapproval of Donald Trump and concern about the cost of living drove the result.
With Democrats now holding both houses it will be very hard for Trump to advance his legislative agenda, but the president still has veto power, so what happens next?