All eyes are on the race to be the next US president, but the battle to control Congress may be almost as consequential.

The next Congress could determine whether the supreme court goes back to having nine justices, whether the USA makes good on its climate promises and whether, for example, Hillary Clinton is impeached, should she be elected president.

If the Senate and the House stay Republican and Donald Trump wins the presidency, he would not necessarily have carte blanche. As much as Trump may want to build a border wall with Mexico, he would not be able to spend the estimated $25bn it would cost until Congress legislated for it. (That’s assuming Mexico does not pay for the wall upfront, as Trump has sometimes promised it would.)

Trump would likewise need Congress’s help to deport undocumented migrants, slap new tariffs on Chinese goods or fine US companies for moving manufacturing overseas. It’s unclear whether the GOP would back him on these issues. But a quick agreement on issues such as repealing the estate tax and Barack Obama’s healthcare law might well be in the cards.



It is extremely unlikely that the Democrats will seize control of the House of Representatives on Tuesday, owing to an overwhelming, 60-seat Republican majority in the lower chamber.

Artful gerrymandering at the state level means there aren’t many toss-up House races this cycle – only 18 out of 435, according to the Cook Political report. Democrats could win every single one of the toss ups and still fall around eight seats short of a House majority.

But the Senate is a different matter, with most analysts putting the Democrats’ chances of overcoming the GOP’s current eight-seat majority and taking the upper chamber at about even.

“It’s basically 50-50,” Harry Enten, a polling analyst with FiveThirtyEight, told CNN on Sunday. “You have in my opinion maybe six or seven seats that are going to really determine this.”

If Democrats controlled the senate, and Clinton were president, the supreme court vacancy could soon be filled – although Republicans have already hinted at a procedural fight to stop that from happening.

As with every aspect of the 2016 election cycle, Trump’s presence is palpable. Some Republican incumbents appear to have been wounded by associations with the GOP nominee. Senator Kelly Ayotte in New Hampshire saw her numbers drop after she was asked at a debate whether Trump would be a good role model for children, and replied “absolutely”.



If Nevada representative Joe Heck loses his senate bid, analysts will point to the record number of Hispanic voters who lined up in the state to cast early ballots for Clinton (and against Trump). Senator Richard Burr in North Carolina may fall victim to the abandonment of Trump by moderate Republicans in his state.



In other races, there is no perceivable Trump drag – and there may be Trump coattails. In Ohio, where Trump and Clinton appear to be neck-and-neck, Republican incumbent Rob Portman is polling 16 points ahead of his opponent, a former governor. And in Missouri, where Trump appears to be crushing Clinton, Republican incumbent Roy Blunt is in a seemingly tight race with the Democratic state secretary of state. In Pennsylvania, incumbent Pat Toomey appears to be running behind his opponent, but not as far behind Clinton as Trump is running in the state.



“It’s just very difficult to understand exactly what’s going to happen,” Enten said.



Races to watch

New York’s 19th congressional district: Big outside money is trying to block progressive star Zephyr Teachout from making it to Washington. Teachout, a law professor, has strong support from senator Bernie Sanders, but her opponent says she’s a carpetbagger.



Arizona’s first congressional district: Republican Paul Babeu, a county sheriff, dropped out of a congressional race in 2012 after an ex-lover, who was also an undocumented Mexican immigrant, outed him as gay and said the sheriff threatened him with deportation if he said anything. Democrat Tom O’Halleran, a state legislator, appears to have the edge.

California’s 49th congressional district: One of the sweetest of all potential pickups for Democrats, because it would send incumbent Darrell Issa, the loathed former chairman of the oversight committee (read: Benghazi), packing. He faces retired Marine colonel Doug Applegate.

North Carolina governor’s race: Will Tar Heel voters make incumbent governor Pat McRory pay for signing the notorious House Bill 2, which allowed discrimination against transgender people in access to public bathrooms? State attorney general Roy Cooper looks strong.

California’s senate race: The moment when state attorney general Kamala Harris, touted as a future national star for Democrats, could step onto the main stage of politics. Representative Loretta Sanchez, like Harris a Democrat, is putting up a fight.

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