(Reuters) -U.S.-light vehicle sales are expected to remain steadfast in August but are showing early signs of a slowdown, S&P Global Mobility said on Monday.

"Rising interest rates, credit tightening and new vehicle pricing levels slowly decelerating remain pressure points for consumers," said Chris Hopson, principal analyst at S&P Global Mobility.

New light vehicle sales in August are estimated to be 1.34 million units, up 18% year-over-year, according to the report.

The automotive research company also lowered its annual forecast to 15.2 million units of new light vehicles estimated to be sold in the U.S. from sales of 15.7 million units projected in July.

Supply of vehicles could be disrupted in North America as negotiations with labor unions have been heated up lately, the report added.

"The greatest threat to the forecast in the near-term surrounds the union negotiations between the United Auto Workers in the US and Unifor in Canada with their respective contracts set to expire in mid-September 2023," said Joe Langley, associate director at S&P Global Mobility.

UAW on Friday said members voted overwhelmingly in favor of authorizing a strike at the Detroit Three automakers if an agreement is not reached before the current four-year contract expires on Sept. 14.