RENO -- Filing done, the top races in the state have come into focus and politics-watchers have a lot to look forward to this season.

Reeling from three consecutive special election losses, congressional Republicans will have their hands full holding on to the 3rd congressional district and, in a watershed year, the 2nd. Control of the state Senate rests on the thinnest of one-seat majorities, and the Democrats' coveted "veto-proof" majority is only one pick-up away. Here's a brief rundown of the races to watch and how they could all play out:

2nd congressional district: Republican U.S. Rep. Dean Heller is being challenged yet again by Democratic former university regent Jill Derby. Heller ran in 2006 as a moderate Republican, but has since moved sharply to the right and now has a record for Derby to run against. He maintains an edge in fundraising, but Derby was endorsed by the Democratic Blue Dog Coalition last week and is expecting a similar endorsement from the Democratic Congressional Campaign Committee's Red-to-Blue program. Getting the Red-to-Blue endorsement will mean significant fundraising help from national Democrats.

Derby lost to Heller in 2006 by less than 13,000 votes when the district had 48,000 more Republicans than Democrats. Today, that advantage for Republicans is only slightly more than 30,000.

Heller, however, can look forward to the advantages of incumbency to try to improve on his 2006 showing. Heller can likely expect a "sophomore surge" in votes and will certainly benefit from the goodwill engendered by his two years of providing constituent services.

Other candidates in the race include Independent American John Everhart, Green Craig Bergland, Libertarian Sean Patrick Morse and Republican James Smack.

3rd congressional district: Republican U.S. Rep. Jon Porter is facing what may be the toughest reelection of an already bruising congressional career. Unlike previous years, when Porter faced relative unknowns, this year he is challenged by former Nevada Senate Minority Leader Dina Titus. Titus, who led Democrats in the state senate for fifteen years, has high statewide name recognition and a considerable fundraising base which she tapped for more than $2 million in her 2006 gubernatorial race.

When Titus ran for governor in 2006, she received more votes than now-Gov. Jim Gibbons in the 3rd Congressional District at a time when the district was considerably less Democratic. Today, Democrats outnumber Republicans by more than 23,000 in the sprawling suburban district.

Porter has more than $1 million cash-on-hand, however, and a head start on Titus when it comes to organizing the district. Also, he has taken stands against the Bush administration since the Democratic takeover of congress in 2006, and will likely run as an independent voice in the Republican Party.

Other candidates in the race include Republicans Carl Bunce and Jesse Law, Democrats Barry Michaels, Carlo "Tex" Poliak and Anna Nevenic, Green Bob Giaquinta, Independent American Floyd Fitzgibbons, Libertarian Joseph Silvestre and Independent Jeffrey Reeves.

Senate District 3: Republican state Sen. Majority Leader Bill Raggio will be facing what could be a tough primary challenge this year from former Assemblywoman Sharron Angle. Angle, who narrowly lost to Rep. Dean Heller in the 2006 CD2 primary, has proven a tough campaigner in the past, but will be running headlong against Raggio's nine terms of service in the Nevada Senate. Two questions will dominate this race until August. First, will Raggio actually go out and work the district as Angle is certain to do? And, where will the Republican Senate Caucus' resources go this year, to defending the dean of the caucus and senate or for those two competitive races in Clark County?

Senate District 5: Republican state Sen. Joe Heck, freshly back from a brief tour in Iraq with the Army Reserve, will be facing Democrat Shirley Breeden in a district that is now 41 percent Democratic to 39 percent Republican. Breeden had previously announced that she would seek the 21st Assembly District seat now held by Republican Bob Beers, but on the last day of filing, announced instead for the 5th Senate District. Despite the voter registration advantage, Breeden will be hard-pressed to give voters a reason to not send Heck back to the state senate, especially when pictures of Heck in Iraq make their way onto thousands of mail pieces. Breeden can look to 2006 election results for hope, however. In that year, Democratic state Sen. Joyce Woodhouse won with 48 percent of the vote in the same district, when voter registration was 41 percent Republican to 39 percent Democratic. Also, potentially drawing votes away from Heck will be Independent American Tony "Grass Roots" Blanque and Libertarian Tim Hagan.

Senate District 6: Republican state Sen. Bob Beers will be challenged this year by Democrat Allison Copening in the most narrowly divided district in the state. Democrats have an edge of only slightly more than 500 voters in the district and both sides have launched voter registration drives there to improve their standing. Beers, who unsuccessfully ran for governor in 2006, is one of the most popular conservatives in the state and has held the line against tax increases and government spending. 2008, however, is a year in which budget cuts are on many Nevadans' minds and as services decrease, they may look for someone to blame.

Assembly District 2: With former Republican Assembly Leader Garn Mabey's retirement, his seat in northwest Las Vegas is open and a target for Democrats. Democrat Carlos Blumberg, who ran against Mabey in 2006, is running again as well as Democrat Meghan Smith. Former Clark County GOP chair John Hambrick is running for the seat and has already amassed an impressive list of endorsements including from U.S. Sen. John Ensign. Other filed Republicans include Ernest Fitzpatrick and "Jack" Surpure. Independent Mark Stefano, Independent American John Kamerath and Libertarian Edward Klapproth have also filed. The seat is 44 percent Republican to 38 percent Democratic.

Assembly District 4: Assemblywoman Francis Allen will be facing what could be a serious primary challenge from Republicans Richard McArthur, Andrew Brownson and Flo Jones. McArthur has been working the district hard and has built some strong relationships, particularly among the Spring Mountain Republican Women. With three Republican challengers in the race, however, Allen's odds have improved as it is likely they will split the protest vote.

Assembly District 5: Republican Assemblywoman Valerie Weber's race for the county commission has left her Democratic-leaning seat open. Working to succeed her is Republican Donna Toussaint, who has been campaigning for months and is one of the highest-priority candidates for the Republican Assembly Caucus. Facing her will be Democratic ex-elementary school teacher Marilyn Dondero Loop.

Assembly District 13: Republican Assemblyman Chad Christensen surprised many observers when it was reported last week that he would not be filing for reelection. He did file Friday, however, improving Republicans' chances of holding the Democratic-leaning seat, but raising questions as to whether he has the "fire in the belly" for a hard-fought campaign. Facing him will be former congressional candidate Andrew Martin, who can pour hundreds of thousands of dollars into the race and has amassed a large volunteer base.

Assembly District 21: Republican Assemblyman Bob Beers will face a primary challenge this year from Jon Ozark, who unsuccessfully ran for Assembly District 10 in 2006. Beers has angered some conservatives by supporting union-friendly legislation and Ozark is likely to put up a serious challenge. If Beers makes it past the primary, he will face Henderson Democratic Club president Ellen Spiegel in a district with only about 400 more Republicans than Democrats.

Assembly District 23: With Democratic Assemblywoman Rosemary Womack's retirement, her relatively safe Democratic district may face a serious challenge from Republican Melissa Woodbury, daughter of Clark County Commissioner Bruce Woodbury. Facing her will be Democrat Allison Herr.

Assembly District 24: Democratic Assemblyman David Bobzien is a Republican target again this year and will be challenged by state education board member John Gwaltney. Gwaltney was endorsed by Reno Mayor Bob Cashell and is already working the Democratic-leaning district. To add to Bobzien's troubles he will also face a primary challenge.

Assembly District 29: Republican Sean Fellows is the star candidate of Republican efforts to pick up a Democratic Assembly seat. Fellows has raised more than $100,000 for his campaign effort and has been organizing for months. Facing him will be Democrat April Mastroluca, whose campaign was announced just last month when Assemblywoman Susan Gerhardt declared her retirement.

Assembly District 40: Democratic Assemblywoman Bonnie Parnell will face a serious challenge from former Republican Secretary of State Cheryl Lau. Despite her four successful campaigns, Parnell's district is primed for a Republican takeover with 38 percent Democrats to 46 percent Republicans.