At 0835 GMT, the FTSE 100 was down 0.3% at 7,284.24.
Oanda market analyst Craig Erlam said: "Equity markets are a little lower on Wednesday as investors continue to watch events unfold in the US for a sense of what impact they'll have on sentiment.
"The impact of the midterms will probably be short-lived, if impactful at all, as far as markets are concerned. Of course, the political implications may be significant if Democrats can manage to retain control of the House and Senate but at this stage, only one of those looks plausible which means deadlock in Washington.
"The bigger takeaway from the election may well be what support there is for Trump-backed candidates and what that does for his own re-election hopes in two years. But that's unlikely to sway the markets now, not with so much else to focus on.
"Investors are more focused on the inflation data on Thursday and whether that will pave the way for a slower pace of tightening in December and early next year."
In equity markets, Aviva (LON:AV) was trading down even as it posted a 10% rise in third-quarter gross written premiums and backed its dividend and capital returns guidance.
Flutter Entertainment edged lower despite boosting its forecasts for annual US revenues after a strong third quarter.
ITV (LON:ITV) was also on the back foot after the broadcaster reported a rise in sales for the first nine months of the year, as its production arm offset a fall in television advertising revenue.
AJ Bell was knocked lower by a downgrade to ‘hold’ from ‘buy’ at Shore Capital.
On the upside, engineer Smiths Group (LON:SMIN) gained as it backed its full-year expectations and said first-quarter growth had accelerated.
Taylor Wimpey (LON:TW) advanced even as the housebuilder reported a fall in its sales rate alongside a spike in cancellations as the mounting cost-of-living crisis dented demand.
Food and clothing retailer Marks & Spencer rose after saying it expects to deliver annual results "similar" to expectations as interim pre-tax profits grew 11.3%. Clothing and homewares sales rose 14% in the six months to October 1, while food revenue was up 5.6%. Group revenue increased 8.5% to £5.5bn.
Market Movers
FTSE 100 (UKX) 7,284.24 -0.30%
FTSE 250 (MCX) 18,661.67 -0.19%
techMARK (TASX) 4,297.89 -0.38%
FTSE 100 - Risers
Smiths Group (SMIN) 1,609.00p 3.71%
Associated British Foods (LON:ABF) 1,479.50p 1.47%
Persimmon (LON:PSN) 1,269.50p 1.24%
RS Group (RS1) 892.50p 1.19%
B&M European Value Retail S.A. (DI) (BME) 377.10p 1.18%
Barratt Developments (LON:BDEV) 390.50p 1.17%
Anglo American (LON:AAL) 3,095.50p 1.03%
Taylor Wimpey (TW.) 96.92p 1.00%
Endeavour Mining (EDV) 1,661.00p 0.79%
Rio Tinto (LON:RIO) 5,151.00p 0.78%
FTSE 100 - Fallers
Aviva (AV.) 423.60p -2.37%
Flutter Entertainment (CDI) (FLTR) 11,610.00p -1.48%
Shell (LON:RDSa) (SHEL) 2,406.00p -1.31%
Harbour Energy (HBR) 384.00p -1.29%
Informa (INF) 565.20p -1.19%
Entain (LON:ENT) 1,309.00p -1.17%
DCC (CDI) (LON:DCC) 4,495.00p -0.93%
Ocado Group (LON:OCDO) 697.60p -0.85%
Hargreaves Lansdown (LON:HRGV) (HL.) 815.80p -0.83%
Scottish Mortgage Inv Trust (SMT) 744.00p -0.80%
FTSE 250 - Risers
Dr. Martens (DOCS) 262.00p 2.34%
Marks & Spencer Group (MKS) 119.70p 2.26%
Ferrexpo (FXPO) 126.70p 2.10%
Redrow (LON:RDW) 447.00p 1.73%
Hochschild Mining (LON:HOCM) (HOC) 59.40p 1.63%
Edinburgh Worldwide Inv Trust (EWI) 173.00p 1.41%
Helios Towers (HTWS) 117.50p 1.29%
Murray Income Trust (MUT) 796.00p 1.14%
Spire Healthcare Group (SPI) 221.50p 1.14%
Just Group (JUST) 64.85p 0.93%
FTSE 250 - Fallers
ITV (ITV) 69.60p -4.87%
AJ Bell (AJB) 338.00p -3.10%
Genus (LON:GNS) 2,862.00p -2.98%
Darktrace (LON:DARK) 351.00p -2.42%
Morgan Advanced Materials (MGAM) 284.50p -2.40%
Wood Group (John) (WG.) 156.65p -2.37%
Wetherspoon (J.D.) (JDW) 476.80p -2.34%
Wizz Air Holdings (LON:WIZZ) 2,078.00p -1.98%
IWG (IWG) 163.75p -1.86%
TP Icap Group (TCAP) 170.10p -1.79%