Two non-politicians, businessman Donald Trump and retired neurosurgeon Ben Carson, dominate the contest for the Republican nomination, together accounting for more than half of the potential vote as support for traditional politicians continues to decline, according to a new Washington Post-ABC News poll.

In the contest for the Democratic nomination, Hillary Rodham Clinton has lost significant ground over the past two months, as she has struggled to manage the controversy over her use of a private email server while secretary of state. She still leads the field of Democrats, but for the first time her support has dropped below 50 percent in Post-ABC surveys, with the biggest decline coming among white women.

Overall, the survey underscored the degree of dissatisfaction toward government and politics that is shaping the campaign. More than seven in 10 Americans say people in politics cannot be trusted. More than six in 10 say the political system is dysfunctional. Sizable majorities of Democrats, Republicans and independents agree with those assessments.

But Democrats and Republicans part ways over the kind of experience they are looking for in the next president. Nearly six in 10 Republicans say they prefer the next president to have experience that comes from outside the political establishment. Only about a quarter of Democrats say the same.

Two-thirds of the Republicans who say they are looking for non-political experience currently support either Trump or Carson – the foundation of the wide division between the two outsiders and the rest of a field made up almost exclusively of traditional politicians. Several of these current or former elected officials registered new lows in the survey.

Their next big chance to reverse their fortunes comes at a debate on Wednesday evening at the Ronald Reagan Library in Simi Valley, California, that will feature the top 11 candidates.

The new poll found Trump to be the favorite of 33 percent of registered Republicans and Republican-leaning independents. That is a jump of nine percentage points since mid-July and a 29-point increase since late May, just before Trump announced his candidacy. He does well with most groups of Republican voters, but his strongest support comes from those who do not have a college degree and those with incomes below $50,000.