Originally posted by @phranny
The next quarterly report comes out about one week before the mid term elections in November. If the number looks good, 3% let's say, the GOP will win seats.
It's highly unlikely and would be virtually historically unprecedented for a President's party to gain seats in the House in a mid-term election:
As stated in PolitiFact, since the Roosevelt era, the President’s Party has only gained seats in the House and Senate during the midterm elections twice — in 1934 and 2002. Those gains were relatively meager, with Bush II gaining 8 seats in the House and 2 seats in the Senate in 2002, and FDR gaining 9 seats in the House and 9 seats in the Senate in 1934. Bush II’s 2002 mid-term election stands out as a particular anomaly, since the country was still emotionally recovering from 9/11, and the Republican Party was able to capitalize and brand the party as synonymous with patriotism. Clinton’s 1998 midterms also warrant a look, as Democrats gained 5 seats in the House while losing none in the Senate. But excluding the midterm election following 9/11, we’re looking at the President’s party gaining seats in both chambers only once since Roosevelt began the modern era of the Presidency. Midterm losses are far more common and tend to be massive, especially in the House. For instance, Roosevelt lost 71 seats in the House in the 1938 midterms, which is the biggest loss of House seats since. Roosevelt lost 55 House seats in 1942. Eisenhower lost 48 House seats in 1958. Lyndon B. Johnson lost 47 House seats in 1966. Bush II ended up losing 30 House seats in 2006, after escaping midterm losses directly after 9/11. Midterm losses aren’t just common, they are the rule. All Presidents since Roosevelt who have served two terms have had at least one midterm election where they lost seats in the House and Senate. Johnson essentially served Kennedy’s second term, and he lost seats in both the House and Senate in 1966. Ford did the same for Nixon, and he lost seats in the House and Senate in 1974. Carter and Bush I only served single terms, and they also both lost seats in the House and Senate in 1978 and 1990, respectively.
There's a nice chart underneath that paragraph laying out the results since 1934.
I still think the odds are good for a "blue wave" election in the House. The Senate is a tough climb for the Dems; they have 25 Senate seats up compared to only 8 for the GOP, so gains are unlikely.