CARACAS, Venezuela — The shadow of the Venezuelan military hangs over Sunday's presidential election, with many people wondering how the armed forces might react if President Hugo Chavez stumbles in his fight to stay in power.

Chavez has spent nearly 14 years consolidating control over state institutions, but ultimately only the military has the clout to determine who will prevail if the election results are close and disputed.

The opposition contends Chavez has already been employing the military in a political role even though the constitution forbids it. His challenger, Henrique Capriles, tweeted a photo this week showing soldiers appearing to shed olive-green fatigue tops in favor of the red T-shirts worn by the "Chavistas" who crowd the president's rallies.

"In my government nobody will be obliged to don the T-shirt of a political party, least of all our soldiers!" Capriles wrote, putting new attention on the military's potentially crucial post-election role.

The information ministry didn't respond to requests for comment on the claim by the opposition, which has long voiced concerns about Chavez putting his loyalists into the armed forces' top commands.

"The armed forces will be the key arbiter of the election process," said Diego Moya-Ocampos, an analyst with IHS Global Insight. He said that will be especially true if Capriles manages to eke out a narrow victory and Chavez's side resists.

Chavez's own background shows how crucial, and divided, the military can be. As a 37-year-old lieutenant colonel, he led a failed 1992 coup attempt that brought him to widespread public attention. A decade later, after he was pardoned for the uprising and then elected president, some military officers joined in a plot that ousted Chavez for two days in 2002. Both times, the coup failed in large part because a sizable share of the military refused to go along.

The last successful coup occurred when troops ousted military-imposed President Marcos Perez Jimenez in 1958, during an era when coups across Latin America were far more common than they are now.

Retired military officers say there are deep divisions within the armed forces, but they believe many of the roughly 8,500 rank-and-file officers who form the core of the 125,000-strong military would accept the voters' choice.

The chairman of Venezuela's joint chiefs, Gen. Wilmer Barrientos, said on national television last month that the military would "heed the constitution and respect the will of the people" in Sunday's vote.

But some Chavistas in the military high command haven't been acting impartially as another six-year term for their boss hangs in the balance.

The defense minister, Gen. Henry Rangel Silva, has been on state-run TV all week, here touring a remodeled military hospital, there touting auto repair shops that he said the government plans to create under partial military control.

In late 2010, Rangel angered many Venezuelans by saying in a newspaper interview that neither the military nor the public would accept an opposition election victory over Chavez. The president later defended the general.

Rangel made headlines again this week with a claim that Capriles plans to dismantle the armed forces.

Capriles, a center-left former governor, had just announced that he had chosen an active general, whom he did not identify, to be his defense minister.

The announcement indicated the military leadership is not entirely in lockstep with Chavez's populist rule, which human rights groups say has consistently violated the civil liberties of its foes.

A recently retired senior general who supports the opposition told The Associated Press that dozens of officers, including generals, remain on active duty but without assigned jobs, effectively shunted aside in favor of Chavez's political loyalists

"There's great turmoil in the institution," said the retired officer, who agreed to discuss the situation only if not quoted by name, because he feared reprisals from the government.

He said Capriles' camp has been holding secret meetings with active-duty officers at which "batteries are removed from cellphones" so eavesdroppers can't listen in.

Rocio San Miguel, president of the independent military watchdog group Control Ciudadano, said Capriles' announcement "unleashed a witch hunt to try to determine" which of the 500 generals and admirals was anointed.

The entire military high command is appointed by Chavez. San Miguel estimates there are 300 hardcore Chavez loyalists in the officer corps, while mid- and lower-level officers aren't necessarily politically allied.

If there is no clear-cut winner in Sunday's vote, or if the opposition wins by a narrow, contested margin, San Miguel believes the greatest threat of violence would not come from the military, but from pro-Chavez militias: "armed bodies that operate outside the law and that in the past have appeared after polls close."

Many Venezuelans believe members of the militias, which are believed to number more than 100,000, are little more than thugs. Their leaders don't report to the armed forces, but rather directly to a military officer under Chavez, San Miguel said.

There has been sporadic pre-election violence. Pro-Chavez activists have tried to block opposition rallies and marches, and two Capriles supporters were shot to death during a campaign caravan last Saturday in Barinas, the president's home state.

Critics have also expressed concern that soldiers could be pressured to vote for Chavez. Members of the military were given the right to vote in 1999 during Chavez's first year in office. Soldiers vote in the polling centers where they're registered, along with civilians.

Electoral officials and political leaders on both sides have assured the public that safeguards are in place to ensure the vote is secret, but some Venezuelans still fear that thumbprint readers used to verify identities at polling stations might have the ability to keep track of voters' choices.

Chavez, who was first elected president in 1998, has surrounded himself with soldiers, active and retired. Five of Chavez's roughly 30 Cabinet ministers are either current or former military officers, including those in charge of health, food and public banks.

They also occupy such vital posts as president of the National Assembly and have been elected governors of some of Venezuela's biggest states.

Some top officials have stronger motives to hope Chavez remains. The current defense minister, Rangel, is among seven members of Chavez's inner circle whom the United States put on its foreign drug kingpins list, accusing them of supplying Colombia's main leftist rebel group with arms and aiding cocaine-trafficking operations. Washington has frozen any assets they might have in the United States and barred Americans from doing business with them.

The U.S. government says Venezuela continues to be the main point of departure for northbound drug flights from South America.