Control of the Nevada Senate is up for grabs next week, with five races in play to determine whether Republicans can retake control of the upper chamber — or if Democrats can claim a big enough majority to exert political muscle over their GOP counterparts and Republican Gov. Brian Sandoval.Democrats hold an 11-10 edge. But the slim majority combined with redrawn districts and some tight voter registration numbers — not to mention thousands of nonpartisan voters — make the battle for control too close to call.In the Assembly, Democrats have a 26-16 majority, and Republicans are hoping to pick up a few seats or at least prevent Democrats from winning two-thirds and becoming a supermajority — a voting bloc that can raise taxes or override a governor’s veto. “We may not be in the driver’s seat, but we’ll be seated in the front seat controlling the GPS,” Assemblyman Pat Hickey of Reno, the Republican caucus leader, said of the Nov. 6 general election. Nine Assembly members — five Republicans and four Democrats — drew no opposition and will skate to re-election.Twelve of the 21 Senate seats are up for grabs. Democrats hold large voter registration advantages in six, Republicans in one. That leaves four Southern Nevada seats and one fiercely contested race in Northern Nevada’s Washoe County to determine whether Democrats or Republicans will set the agenda in the upper chamber come February. Republicans need to win four to take control. Democrats, if they can capture all five, will hold a supermajority. “We feel good about where we are right now,” said Sen. Michael Roberson, R-Las Vegas and the presumed GOP leader. “Everything we’re seeing shows five close competitive races, which we thought all along. While Democrats hold a voter advantage, Roberson said Republicans “have an edge because we have better candidates.” GOP candidates also have a money advantage, according to campaign finance records. But Sen. Mo Denis, D-Las Vegas, said Democrats’ strength will be getting voters to the polls.“We have a lot of volunteers. We don’t have to spend as much as they do,” he recently told the Las Vegas Review-Journal.District 15 in southwest Reno is at the epicenter of the power struggle, where Republican Sen. Greg Brower is challenged by former Democratic Sen. Sheila Leslie. Leslie spent 12 years in the Assembly before her election to the upper house in 2010. She resigned that safe seat this year when a home she had bought earlier was redrawn into Brower’s district by reapportionment. The candidates combined have raised more than $1 million, though Brower’s haul has eclipsed Leslie’s by about $200,000. Republicans have a voter registration edge of 900, but nonpartisans total more than 13,000 and will decide the outcome.Brower was appointed to the seat in January 2011 — just before the start of last year’s session — to replace longtime Republican Sen. Bill Raggio, who retired midterm because of health concerns. Raggio died a year later. A former U.S. attorney in Nevada, Brower soon began campaigning for an open congressional seat, but his party’s nomination went to Mark Amodei, who won a special election and is seeking re-election next week.In Southern Nevada, Republicans set their sights early on Districts 5 and 6 — both being vacated by Democratic lawmakers — to chalk up seats in the red column. While a surge in voter registration gives Democrats an edge, each district has more than 11,000 nonpartisan voters who will decide the outcome.Former Democratic Sen. Joyce Woodhouse faces Republican Steve Kirk in the District 5 race to replace Democrat Shirley Breeden, who did not seek re-election. Kirk is a former Henderson city councilman. Democrats outnumber GOP voters by 3,475.In District 6, the Democrats’ lead is 4,800 for a seat they’re trying to retain after Sen. Allison Copening did not seek a second term. Republican Mark Hutchison, who represented Nevada in the 26-state lawsuit against the federal health care law, is squaring off against Democrat Benny Yerushalmi, who lost a 2010 state Senate bid. Yerushalmi, a businessman, also serves on the Commission on Economic Development having been appointed by Republican Gov. Brian Sandoval.It’s a similar scenario in District 9 to replace Republican Elizabeth Halseth, who resigned in February halfway through her first term. Democrats outnumber Republicans by 4,513, giving Democrat Justin Jones an advantage over Republican Mari Nakashima St. Martin.Republicans hold a slight edge — 410 — in the Senate District 18 race between Assemblyman Scott Hammond, the GOP candidate, and Democrat Kelli Ross, the wife of Las Vegas Councilman Steve Ross. As in the other swing districts, nonpartisans voters total more than 11,000. District 18 was a rural, Northern Nevada conservative domain of Sen. Mike McGinness of Fallon, who was forced out by term limits. It was moved to southern Nevada’s Clark County last year when voting boundaries were redrawn by a court panel to account for population shifts, as required by law every 10 years.