Iraq imposed a nationwide security lockdown Friday before key regional elections with blanket measures not seen since the deadliest years of the insurgency, underscoring the high stakes for Iraqi leaders desperate to portray stability after nearly six years of conflict.

Although violence is sharply down — and with pre-election attacks relatively limited — authorities were unwilling to take any risks. They ordered cars off city streets, sealed borders and closed airports.

The top-to-bottom precautions show that the consequences run deeper than just the outcome of today’s ballots for 440 seats on influential provincial councils across Iraq.

Voting carried off without major attacks or charges of irregularities would give a critical boost for Iraqi authorities as the U.S. military hands over more responsibilities. But serious bloodshed or voting chaos could steal momentum from supporters of a fast-paced withdrawal of U.S. combat troops next year.

The election is also a possible dress rehearsal for bigger showdowns later this year when the U.S.-allied government of Prime Minister Nouri al-Maliki could face challenges for power.

“Our security is very well prepared,” said the deputy interior minister, Iden Khalid.

Yet the full-scale clampdown also brought back an aura of some of Iraq’s most unstable days, including 2005 elections, which many observers believe set the stage for sectarian violence a year later.

Traffic bans were ordered for Baghdad and other major cities. The closely monitored frontiers with Iran and Syria were among borders that were sealed. A nighttime curfew also was in place, apparently to block extremist groups that plant roadside bombs under cover of darkness.

Double-ring cordons are planned for the thousands of polling sites — in schools, offices and civic centers — stretching from the foothills in the far north to the Persian Gulf in the south. In many places, women teachers and other civilians were recruited to help search for possible female suicide bombers.

The U.S. military has assisted Iraqi forces in the security preparations and plan patrols during the elections. But American commanders insist they are on the sidelines and will intervene only if needed.

Polls opened early today at 7 a.m. in Iraq (10 p.m. CST Friday) and were scheduled to close 10 hours later. Results are not expected for several days. But it could take weeks of dealmaking to determine which parties have gained control of key areas such as Baghdad, the Shiite-dominated south and former insurgent strongholds of western Anbar province.

More than 14,000 candidates have joined the races, marking the first time large numbers of Iraqi politicians have openly campaigned since the U.S.-led invasion that toppled Saddam Hussein in 2003. In past elections, voters picked from parties, and individual candidates mostly stayed out of the public eye for safety.

But the flood of candidates also brings potential confusion. There are more than 2,600 alone in the Baghdad area for 57 seats, turning the ballot paper into a dizzying exercise in picking both a party and candidate.

“We are tasting the fruits of democracy,” al-Maliki said at a campaign stop for some political supporters.

But it hasn’t been without some pain. Gunmen killed three candidates in attacks Thursday — slayings typical of recent weeks: gangland-style hits or small bombings but few large blasts with major casualties.

At the Baghdad funeral of one of the slain candidates, Omer Farooq al-Ani, mourners covered his coffin with an Iraqi flag and his campaign poster, which carried the slogan: “With us, your life has value.”

The provincial councils have no direct sway in national affairs, but carry significant authority through their ability to negotiate local business deals, allocate funds and control some regional security operations.

In this election, they also may offer a road map for coming political tussles and trends. The Shiite-led government may have the most hanging in the balance.

Al-Maliki’s Dawa bloc has been facing off against Iraq’s largest Shiite party, the Supreme Islamic Iraqi Council, which has close ties to Iran but has also forged a rapport with Washington.

A strong showing by the Supreme Council would likely feed its ambitions to claim control of the government in national elections this year and to establish a self-governing region in the oil-rich Shiite south.

Al-Maliki and many other Iraqis believe that could lead to greater Iranian influence and stoke sectarian divisions.