Popular wisdom suggests that Donald Trump expects to lose the House of Representatives, although Democrats don't believe anything is in the bag.
In the lower chamber there are about 30-35 tight races right across the country.
The key may be the liberal, affluent voters - if they vote for the economy they back Republicans. If they vote for their social values, they go Democrat. That's a big if which decides who controls one house of congress.
The senate is easier for Trump's party to keep, as a lot of the tight races are in states that went for him.
Interesting ones will be places like Missouri, Indiana - Democrat senators sitting in very red states. Many of them are campaigning more like independents - cautious not to mention their own party , so they don't scare off Conservative voters.
The red meat state
But all eyes are on Texas where a young skateboarding Democrat, Beto O'Rourke, has got a truly Republican state within his grasp.
His opponent is Ted Cruz - who clashed with Trump in 2016. But the president has supported him this time around - campaigning there often.
And Texas is a red meat, red heart state with open carry gun laws. It's almost unthinkable they could elect a democrat. But anything could happen there this race.
In Arizona - state of the late John McCain - two women are vying for the senate. The Republican is a former fighter pilot and its neck and neck.
In Nevada a Republican is trying to hold on in a state won by Hillary Clinton. And this part of the world is getting less white and more Latino - which often means more blue voters.
Florida is always a nail biter. The fourth term Democrat fighting the former Republican governor. They've clashed sharply on gun violence in a state that saw the young rise up after a mass school shooting.
There are nearly 500 races across the country. Will this be a referendum on Trump? The president would like to think so.