DENVER — Republicans hoping to topple Democrats' one-seat majority in the Colorado Senate will take a first step next Tuesday when they pick their candidates in two key legislative races in the Denver suburbs.

Their challenge, political observers said, is making sure they select candidates who can appeal to the crucial bloc of independent voters during the general election, instead of picking candidates that may be seen as too conservative to win in November.

"The legislative races are important for two reasons: They have a very practical impact on what party controls the state Senate in January. And secondly, they're important as an indicator of where the Republican Party is going and how strong its self-destructive mode remains," said Eric Sondermann, an independent political analyst in Colorado.

Republicans are still lamenting their choice to run for governor in 2010, when they selected political newcomer and tea-party favorite Dan Maes, who never mounted much of a challenge to current Democratic Gov. John Hickenlooper.

The high-stakes primaries are in Senate District 19, which covers Lakewood. That's where the Republican candidates are Mario Nicolais, a GOP attorney who served as one of the map-drawers during state redistricting in 2011, and Tony Sanchez, who has experience managing nonprofits and who has worked on outreach to Latinos for the party.

In Senate District 22, Lang Sias, a veteran of both Gulf Wars who is considered a rising star in the Republican Party, faces Republican Laura Woods, who has owned a court-reporting businesses and was involved in two recall petition efforts against former District 22 Sen. Evie Hudak. Hudak was targeted because she voted with fellow Democrats to pass gun-control laws last year.

Hudak resigned during the second recall effort before signatures were turned in, and Democrats selected Rachel Zenzinger to take her seat and keep a one-vote majority in the chamber. Sias and Woods are vying to challenge Zenzinger.

Nicolais and Sanchez are trying to run against Democratic Sen. Andy Kerr. Zenzinger and Kerr don't face primaries.

Both districts are considered toss-ups, and political analysts see Nicolais and Sias as the more established candidates who can attract independent voters in November. Nicolais was a strong advocate for the passage of civil unions for gay couples last year, and Sias narrowly lost to Hudak in 2012.

Before Hudak stepped down, gun-rights advocates successfully recalled two Democratic senators in September, putting Democrats in a tenuous 18-17 majority in the chamber and raising the GOP's hopes of being in power there again.

"If Republicans want to win in November, the decisions we make in June will make or break our chances," said Rob Witwer, a Republican who previously served in the state House. Witwer was also one of the Republicans who worked on state redistricting three years ago.

Sanchez dismisses the notion that he's the less viable candidate in the SD 19 Republican primary, noting that he won more votes than his opponent in the March GOP assembly and that he has outraised Nicolais $39,100 to $21,700.

"We the people are speaking very clearly," he said.

Woods did not respond to call for comment.

In the state House, there are eight Republican primaries. However, the GOP's chances of reclaiming control of the House are far slimmer than in the Senate because Republicans have more ground to cover. The Democrats' advantage in the House is 37-28.

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