By Jesse Schneider

Anger towards a sitting president and frustration with their economic fortunes often drive midterm election voters to the polls. And according to Charlie Cook, this means journalists covering midterms should pay attention to such factors to know if a “Republican Revolution” or a “blue wave” is on the way.

“Midterm elections are a lot more explosive than they used to be,” Cook said, noting that angry voters vote in disproportionate numbers.

In a session with Paul Miller fellows, Cook, editor and publisher of The Cook Political Report, detailed the polling trends journalists should look for in the lead-up to a midterm election.

One is the public’s perception of the economy. If voters believe the economy is thriving and credit the president for it, big changes in Congress are unlikely. But if voters think the president isn’t putting up good economic numbers – or if there’s an economic downturn – a wave could be imminent.

Cook said presidential job approval numbers have become a reliable predictor of election results. In the eight midterm elections between 1986 and 2014, he noted, four presidents had a job approval rating of 50 percent or better in the final Gallup poll before the election and the average net change in the House and Senate was zero. When the president had a job approval rating of 46 percent or lower, however, the average was a 40-seat loss in the House and a seven-seat loss in the Senate.

That’s why Donald Trump’s 2018 approval ratings, consistently lower than the 46 percent threshold, alarm Republican strategists. “There is considerable evidence that this is hurting Republicans down ballot,” Cook said.

According to Cook, the national generic ballot, which asks respondents if they favor the Democratic Party or the Republican Party, is “a pretty good yardstick” of what could happen. But he also cautioned against relying too heavily on such polls: Because of both demographics and redistricting, Democratic voters are concentrated in cities whereas Republican voters are spread more evenly across the country. That means much of the Democratic advantage reflected in the national generic poll is in urban areas where the party already holds seats.

Finally, Cook encouraged journalists to spend quality time with pollsters and learn how to interpret polls.

“All polls are not to be treated equal,” he warned; journalists should focus on RealClearPolitics or 538 poll aggregates rather than “cherry-picking” specific polls. Cook also pointed to NBC/WSJ polls as particularly reliable and singled out Gallup’s presidential job approval rating poll because it asks voters the same question and uses the same methodology week after week.