According to the outlet, the November vote will likely herald the start of the heated presidential re-election fight, which will require the president to ensure that his team fully shares his views.
Meanwhile, relations between Trump and Mattis have recently soured over multiple disagreements, the media outlet said. The two politicians have reportedly been at odds over the policy on NATO, the issue of military drills with South Korea and even the assessments of the effectiveness of the US decision to withdraw from the Iran nuclear deal and reinstate sanctions against Tehran.
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In November, US voters will go to the polls for the midterm elections to pick candidates to fill 435 seats in the House of Representatives and roughly a third of the 100 seats in the Senate. The outcome will determine if the Republican Party continues to control Congress.