The heated San Diego mayoral primary rumbled to an end today, with voters in the city heading to the polls to choose between incumbent Jerry Sanders and his Republican challenger Steve Francis.

Polls conducted in the days leading up to the primary show Sanders, a former city police chief, in the low 40 percent range, with Francis, a wealthy businessman, receiving in the mid 30 percent range. Either candidate will need to win 50 percent of the votes to avoid a November runoff between the two.

Tom Shepard, Sanders's campaign manager, expressed confidence that the first term mayor was ahead and that there would not be a runoff.

"The only open question remains if we'll get over the 50 percent threshold," said Shepard. "We think we will."

Charles Gallagher, the campaign manager for Francis, said the campaign was counting on a high turnout of independent, reform-minded voters who wanted a change of leadership in City Hall.

"This is gonna' be close," Gallagher said when asked if Sanders would be kept under 50 percent. "My goal is to win outright."

With low turnout reported across the state, it was unclear if the Francis campaign's hopes would come to fruition. Gallagher said the campaign believed about 200,000 people in all of San Diego County had cast ballots, a number that does not give an indication to the city's absentee turnout.

The race for the city's top job has been a heated affair featuring two men who competed against one another in the 2005 mayor's race and clearly have no love lost for one another. After a forum several months ago, the plain-spoken Sanders swore at Francis.

Despite Francis investing more than $4 million of his own cash to go after Sanders for his leadership on a numerous issues, Sanders has maintained a lead in the race. But the mayor was forced to dodge a bullet when, several weeks ago, his then-campaign manager was found to have given a minor candidate in the race a statement to read in a forum targeting Francis. The campaign manager, Michael McSweeney, resigned shortly after.

While the Francis side has argued that the event fits into a broader pattern of disreputable behavior on the part of Sanders, the mayor's side says the incident has done little to sway the balance of the race. "You could argue that to some extent it diminished our momentum," said Gallagher, a San Diego-based media consultant. "But it took place at a time in which we were going up."