The White House says it cannot intervene in the New York City public transit strike, but it has encouraged the parties involved to resolve their differences.

A White House spokesman, Scott McClellan, told reporters Wednesday that federal mediators have offered to help resolve the conflict over city transit workers' pay and pension issues.

Meanwhile, New Yorkers commuted to work for the second day on foot, on bicycle, or crowded four-at-a-time into taxi cabs. The city's subway and buses shut down early Tuesday after talks deadlocked between the city and the Transport Workers Union. Later that day, a judge imposed a fine against the union of $1 million for each day of the strike.

Merchants are concerned about plummeting sales just before the Christmas and New Year holidays - normally the busiest shopping days of the year.

Some information for this report provided by AFP.