Texas voters will select party nominees in 37 primary runoff elections on Tuesday, with races ranging from the U.S. Senate down to district judge.

Compared to past runoff elections, early voting has been high but still represents only 3.3 percent of registered voters. Since ideologically-motivated voters are more likely to vote, low turnout gives them a disproportionate influence on the outcome of elections such as this one. Here are five things to watch for in Tuesday's runoff elections.

— Who controls the Republican Party of Texas?

For more than a decade, Gov. Rick Perry and veteran politicians such as Lt. Gov. David Dewhurst have maintained authority and unity over the Republican Party of Texas. Their endorsements and support were critical to a new candidate's chance for success. Ted Cruz's performance in the May 29 U.S. Senate vote shocked many Republican operatives in Austin, who until then had never taken his candidacy seriously. Now the rookie politician is giving Dewhurst a literal run for his money, forcing the oil and gas man to spend $16 million on his own election. If Cruz wins, he will have slain a giant using millions of dollars from tea party members and conservative groups from outside of Texas. The message then will be clear: Perry no longer controls Republican politics in Texas; the tea party does.

— Are Democrats paying attention?

Former state Rep. Paul Sadler faced three challengers in the May 29 primary and ended up in a runoff against one who made no effort to mount a statewide campaign. The number of ballots cast in Sadler's race against Grady Yarbrough will give a good indication of whether Democrats are paying attention in a state where Republicans hold every statewide office. Texas Democrats have the longest losing streak in the nation in statewide elections, and this race will give some indication if they have any hopes of changing that record in November.

— How conservative will the Republicans be in the Legislature next year?

Conservative activists have invested heavily in 10 Texas House runoff races and one Texas Senate runoff in hopes of pushing the already conservative Legislature further to the right. Meanwhile, mainstream Republican groups are supporting non-tea party candidates. The starkest contest is in the Texas Senate race between long-serving Sen. Jeff Wentworth and tea party insurgent Donna Campbell, where both sides have spent tens of thousands of dollars for control of the conservative San Antonio district. Other races include Sid Miller versus J.D. Sheffield in District 59, Bill Keffer against Jason Villalba in District 114, Jeff Leach versus Jon Cole in District 67 and Drew Springer against Trent McKnight in District 68. Unlike in 2011, Republicans will not have another 101-49 super-majority in 2013. That means Republicans will either have to compromise with Democrats or be prepared to do nothing at all. The latter is the preferred stance of many tea party members and could be the outcome if the tea party gains greater control of the Republican caucus in the Legislature.

— How welcoming are Republican voters to newcomers and Hispanics?

When state Rep. J.M. Lozano announced his defection from the Democratic Party earlier this year, Gov. Rick Perry and other top Republicans warmly embraced him as part of the future of the party in Texas. Republican primary voters, however, have not always been as welcoming, particularly to those with Spanish surnames. Lozano is in a runoff in South Texas against Bill Wilson, and Rep. Chuck Hopson, who defected in 2009, faces Travis Clardy in East Texas. Incumbent Texas Supreme Court Judge David Medina faces a challenger in John Devine. These races will reveal a lot about where Republicans stand on diversifying their party.

— Is a new guard emerging in the Democratic Party?

The biggest races for Democrats in the July 31 runoffs are for three U.S. House nominations in Dallas-Fort Worth, San Antonio and South Texas. In all three races, candidates with ties to the past are running against people with less experience in the Democratic Party establishment. In San Antonio, former U.S. Rep. Ciro Rodriguez is running for a chance to retake his old seat against state Rep. Pete Gallego, an emerging figure in the party. In Dallas-Fort Worth, state Rep. Marc Veasey, a young African American from Fort Worth, is running against former state Rep. Domingo Garcia, a long-time Hispanic activist from Dallas. And a 20-year aid to former U.S. Rep. Solomon Ortiz is running against Filemon Vela, who is running his first campaign. The Democratic Party is undergoing tremendous changes at the moment, and these races could give an indication of how quickly.