By Tim Reid and Nolan D. McCaskillWASHINGTON, Aug 4 (Reuters) - Progressive candidate Abdul El-Sayed held a narrow lead over U.S. Representative Haley Stevens in Michigan's Democratic U.S. Senate primary on Tuesday, though the outcome of a race viewed as a major test of the Democratic Party's future remained uncertain.With 42% of the estimated vote counted, CNN showed El-Sayed leading Stevens by 49.8% to 46.5%.

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Michigan Democrats have voted in a closely watched U.S. Senate primary contest between U.S. Rep. Haley Stevens and progressive Abdul El-Sayed