Mexico picked the head of the national intelligence agency as the country's new interior minister on Thursday, beefing up the job's security profile as the government attempts to bring violent drug cartels to heel.

Alejandro Poire, director of the Centre for Research and National Security (CISEN), succeeds Francisco Blake, who was killed in a helicopter crash on Friday.

Poire, 40, has never held elected office, and spent more than a year staunchly defending President Felipe Calderon's army-led crackdown on the drug gangs as national security spokesman before he moved to the CISEN in September.

The bloody conflict against the gangs has dominated Calderon's presidency, damaging support for his conservative National Action Party and eroding his own popularity.

Crime is the biggest threat to our society and our citizens, Calderon said in a televised address, noting that he had chosen Poire because of his profound knowledge and his vast experience in security matters.

More than 45,000 lives have been lost in drug-related violence since Calderon sent in the army to crush the gangs shortly after he took power in December 2006.

Calderon has staked his reputation on restoring security to Mexico and analysts say he needs to make clear progress to give his conservative National Action Party (PAN) a chance of retaining the presidency when elections are held in July 2012.

Calderon is barred by Mexican law from running again.

As interior minister, Poire will also play a key role in ensuring the 2012 elections run smoothly. The trained political scientist is an expert on the Mexican electoral process.

Latest surveys show Calderon's PAN polling around half as much support nationally as the opposition Institutional Revolutionary Party (PRI). The centrist PRI ruled Mexico for 71 years until being ousted in 2000.

PLACING BETS

Poire, 40, will be Calderon's fifth interior minister. Blake, who died with seven other people in the helicopter, was the second interior minister to die in an aircraft crash.

The interior minister was for years viewed as the number two to the president, though Blake, who took the job in July 2010, had a lower profile than many previous incumbents.

A loyal supporter of Calderon, Poire steadfastly backed the drug war strategy during some of the conflict's most testing moments as national security spokesman.

Jose Luis Pineyro, a security expert at Mexico's Autonomous Metropolitan University, said the appointment of Poire showed Calderon was placing his bets firmly on being able to convince voters his drive against the cartels was paying off.

He has no other option. He's failed to live up to the other two major pledges he made as president: generating more jobs and cutting poverty. Poverty has risen, said Pineyro. Poire will act as a kind of public face (on security).

A Harvard graduate who later worked as an academic, Poire was an adviser to Calderon early in his presidency.

Poire blamed lax U.S. gun laws for allowing high-powered weaponry to reach Mexico and arm the cartels. The entry of U.S. arms into Mexico has been a regular bone of contention between Mexico and Washington during Calderon's presidency.

(Editing by Eric Walsh)