Warning signs pile up for Trump's Republicans as midterm campaign enters final sprint

The final sprint toward the US midterm elections is beginning with Donald Trump's Republicans facing a difficult political problem: the president's deep unpopularity could cost them their narrow majorities in Congress.

The unofficial campaign launch comes on Labour Day Monday, with only two months left before the November vote. Election experts say midterms are above all a referendum on the occupant of the White House. In Trump's case, that pattern carries particular weight after nearly a decade in which he has remained the country's dominant political figure.

The stakes are especially high for the White House. Democrats appear likely to win a majority in the House of Representatives, which would give them the power to open damaging investigations into Trump's administration and force the White House to compromise on most legislation. Democratic leaders have already promised probes into what they describe as corruption by Trump.

The Senate contest remains too close to call. Trump could therefore face stiff political headwinds during his final two years in office, even as Republicans fight to protect their hold on Congress.