Former president Barack Obama has criticised Donald Trump over inflation as Democrats and Republicans step up their campaigns in Michigan, where a closely watched contest for a US Senate seat could help decide which party controls the upper chamber of Congress.
Both men are due to support their party's candidates in the state over the final weekend before the election on 3 November. The race is one of several that analysts see as crucial to the balance of power in Washington, and the presence of two of the most prominent figures in American politics underlines how much is at stake.
According to a forecasting model built by Thomas Miller, a data scientist and professor at Northwestern University, Democrats have gained ground in recent weeks. The model starts from prediction markets, mainly Kalshi and Polymarket, which Miller chose because they have the largest trading volumes, and adjusts their prices into probabilities using statistical methods. Miller says the results are highly volatile and could shift considerably before polling day.
The same model gives Democrats a 78 per cent chance of winning a Senate majority, based on figures for the Senate race as a whole. Miller's calculations show Democrats leading in 18 of the 35 contested races, against 17 for Republicans. Republicans are currently ahead in North Carolina, Ohio, Texas, Alaska and Maine, while Democrats hold firm in seats such as Michigan, where Miller puts their chances at 68.6 per cent, and Georgia, at 94.9 per cent.
Miller argues that the races are moving together rather than independently. In his view, the broad direction of the Senate contest is strongly influenced by Trump's public statements and actions, which tend to lift or depress Republican odds across most states at once. On 19 September, his forecast gave Republicans almost a 36 per cent chance of retaining control of the Senate. By late on 23 October, that figure had fallen to 22.5 per cent.
The model has its limits, and Miller himself stresses that it may not prove the most accurate. It does, however, suggest that the races are less close than recent polls have shown, and that the political climate around Trump may be working against Republicans. Obama's attack on the president's handling of inflation adds to a campaign in which the cost of living is likely to remain a central issue for voters in Michigan and beyond.