BUENOS AIRES (Reuters) - Argentine President Mauricio Macri s preferred candidate was leading former President Cristina Fernandez in an election for a Senate seat in Buenos Aires province, with 24.5 percent of polling booths counted. Esteban Bullrich, Macri s former education minister, had 42.9 percent of the vote counted compared with 35.9 percent for Fernandez in the province that is home to nearly 40 percent of voters.  
Macri ally leads Argentina Senate race against former president