Vote until 11:59 ET; many races can be swayed

As the voting window for the 2015 Esurance MLB All-Star Game Ballot heads to its finish at 11:59 p.m. ET on Thursday, there are several key races for starting position players in the American League and National League that are coming down to the wire.

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The ballot has already eclipsed 500 million votes, exceeding the record of 391 million votes in 2012.

With that in mind, here's a look at six close races on this year's ballot, and the cases for each of the candidates involved.

In the AL, there are tight races at second base, third base, designated hitter and in the outfield.

• Astros second baseman Jose Altuve (7,282,934 votes) is narrowly trailing the Royals' Omar Infante (7,514,642). Altuve leads the AL with 23 stolen bases and entered Thursday riding a 10-game hit streak. A two-time AL All-Star, Altuve led the Majors with 225 hits last year. This season, he's already tied his career high with seven home runs.

Infante is one of five Royals who entered this week in line to start the All-Star Game. He's hitting .230 with 16 doubles and 23 RBIs through 69 games.

• Blue Jays third baseman Josh Donaldson (11,738,206) is the top overall vote-getter after receiving 2.7 million votes last week to move past the Royals' Mike Moustakas (10,372,868) at the hot corner.

Donaldson already has the most votes for any player in history, surpassing Josh Hamilton's tally of 11,073,744 in 2012. Donaldson has certainly earned the support, hitting .302 with 20 doubles, 19 homers and a .904 OPS in his first season in Toronto.

Moustakas got off to a hot start, batting .356 in April. He leads the AL with a .340 average in night games and has multiple hits in 25 games this year.

• Things could go either way at designated hitter, where Seattle's Nelson Cruz (8,891,784) and Kansas City's Kendrys Morales (8,686,879) have been going back and forth since balloting opened.

Cruz got off to a scorching start with his new club, belting 10 homers in his first 22 games with the Mariners. He tallied eight homers in May before hitting just one in June, but he went deep on Wednesday -- his 35th birthday -- to reach 20 for the year. The slugger also has a .307 average, .928 OPS and 10 doubles.

Morales is hitting .287 with 10 homers, 20 doubles and 50 RBIs. He's second in the AL with 36 two-out hits, while his .360 batting average (36-for-100) ranks fourth in the league.

• Angels star Mike Trout (11,461,212) is holding off Kansas City's Lorenzo Cain (10,418,343) for the top outfield spot, while the Royals' Alex Gordon (8,934,052), Detroit's Yoenis Cespedes (7,532,254) and Toronto's Jose Bautista (7,401,632) are battling for the third and final starting spot.

Trout, a unanimous pick for the 2014 AL Most Valuable Player Award, is a virtual lock to earn a starting nod. He's hitting .303 on the season and mashed home run No. 21 on Wednesday.

With the support of an energized Royals fanbase, Cain could surge to the top spot. Either way, it's a good bet he'll start for the AL. Cain is having a great all-around season, hitting .299 with 25 extra-base hits and 15 stolen bases through 68 games.

Gordon leads his club with 35 walks and has a .267/.382/.432 slash line with nine homers and 32 RBIs through 71 games.

In his first season with the Tigers, Cespedes is once again putting up solid numbers with an .808 OPS, 10 homers and 22 doubles through 76 games. He was an All-Star for the first time in 2014 and has won the Home Run Derby each of the last two years.

Bautista, meanwhile, leads the AL with 58 walks to go along with 16 home runs, 53 RBIs and an .895 OPS through 73 games.

In the NL, starting spots are up for grabs at third base and in the outfield.

• Reds third baseman Todd Frazier is trying to surpass the Cardinals' Matt Carpenter to give the home crowd in Cincinnati at least one starter. As of the most recent voting update, released on Monday, Carpenter (6,252,327) was leading Frazier (6,189,347) by a slim margin.

Carpenter is hoping to become just the third Cards third baseman to earn a starting assignment, joining Joe Torre (1971-72) and Scott Rolen (2003-05). A two-time All-Star reserve, Carpenter has eight home runs, 21 doubles, 37 RBIs and a slash line of .279/.378/.461 through 70 games.

Frazier, meanwhile, is among the top performers in the NL in a number of offensive categories with 25 homers, 22 doubles and 54 RBIs through 76 games.

• Nationals slugger Bryce Harper (11,363,949) is a lock to earn a starting outfield spot in the NL, but there are four players in a tight race for the other two spots: Giancarlo Stanton (6,062,318), Matt Holliday (5,454,953), Nori Aoki (5,115,422) and Andrew McCutchen (4,577,646).

Stanton, Holliday and Aoki are on the disabled list.

Stanton leads the Majors with 27 home runs, but he is expected to miss at least three more weeks after undergoing surgery on his left hand on Sunday. If he's voted a starter, an injury replacement would be needed.

Holliday is working his way back from a strained right quad, but he said on Sunday he would go to the All-Star Game if selected, and there's a chance he could be able to play. Holliday had a .303/.417/.421 slash line with three homers and 10 doubles in 52 games before being injured.

Aoki has been a solid pickup for the Giants, hitting .317 from the leadoff spot before fracturing his right fibula last month. He will be in a cast for at least another week, so it's unlikely he would be able to play in the All-Star Game.

McCutchen has a strong case to be an injury replacement, but he could still be voted in. He's been on an offensive tear of late to raise his average to .295 to go along with nine homers, 20 doubles and 45 RBIs through 75 games.

Fans can cast their votes for starters at MLB.com and all 30 club sites -- on their computers, tablets and smartphones -- using the 2015 Esurance MLB All-Star Game Ballot until Thursday at 11:59 p.m. ET. For the first time, voting is exclusively online, where fans may submit up to 35 ballots.

Fans may also receive the ballot by texting VOTE to 89269 (USA) or 101010 (Canada). Or text VOTA for a ballot in Spanish. Message and data rates may apply. Up to five messages. No purchase required. Reply STOP to cancel. Reply HELP for info.

The 2015 All-Star starters will be unveiled on Sunday at 7:30 p.m. ET on the Esurance All-Star Starters Selection Show on ESPN. Then on Monday at 7 p.m. ET, the All-Star reserves, pitchers and Final Vote candidates will be announced on the Esurance All-Star Selection Show on ESPN, immediately after which fans can return to MLB.com to begin casting their 2015 Esurance MLB All-Star Game Final Votes for the final player for each league's All-Star roster. Final Vote ends Friday, July 10, at 4 p.m. ET. On Tuesday, July 14, watch the 2015 All-Star Game live on FOX, and during the game visit MLB.com to submit your choice for the Ted Williams Most Valuable Player Award presented by Chevrolet via the 2015 MLB All-Star Game MVP Vote.

MLB.com will provide extensive online coverage of All-Star Week festivities.

The 86th All-Star Game will be televised nationally by FOX, in Canada by Rogers Sportsnet and RDS, and worldwide by partners in more than 200 countries via MLB International's independent feed. ESPN Radio and ESPN Radio Deportes will provide national radio coverage of the All-Star Game. MLB Network and SiriusXM will also provide comprehensive All-Star Week coverage. For more information, please visit allstargame.com.