Twenty-eight innocent people, including 20 primary students, have been slaughtered in a mass shooting at an elementary school in the US state of Connecticut. Their blood and tears demand no delay for the US gun control.

The massacre has triggered a new debate on gun control in the United States. However, this time, the public feels somewhat tired and helpless.

The past six months have seen enough shooting rampages in the United States. Just three days ago, three people were shot dead at a shopping mall in Oregon. Two weeks ago, a football player shot his girlfriend dead and then committed suicide. Five months ago, 12 people were killed and 58 wounded in a shooting spree at a midnight screening of a Batman film in Colorado.

However, these are only part of the gun violence which has drawn the whole country's attention. Every time a tragedy occurs, there are renewed appeals for gun regulation. However, the calls disappointingly always fail.

Regulation of private gun ownership has been a sensitive issue in the US for a long time. Americans own 280 million guns, with 34 percent of US families possessing the deadly weapon. Gun lobbies, such as the National Rifle Association (NRA), are very influencial.

Centering on issues such as whether citizens can bear arms, and whether the government has the right to ban guns, the opposing camps have debated hotly for years.

Electoral politics is another important reason for the failure of gun control efforts. The Democratic Party has historically paid a price for its gun control efforts.

The Clinton government launched a series of gun control policies at the end of last century. And the Democrats lost the Congressional election in 1994 and the presidential election in 2000, with the shadow of the NRA present in both defeats.

The terrifying mass shooting in Colorado happened in an election year. As a result, neither of the Democratic nor the Republican party were willing to step up gun control, due to possible political ramifications.

For all that, the latest heartbreaking deaths of the 20 schoolchildren aged five to 10 have made the crime especially unbearable. Many people can't help but turn to the dim hope once again: the gunman's cruelty and evil may provide a strong momentum and broader public support for the restart of gun control efforts. Moreover, with no re-election pressure, President Obama is currently in the best position to promote it.

Obama said of the latest tragedy the country had "been through this too many times," and it was time to put aside political differences and "take meaningful action to prevent more tragedies like this."

Some people have noticed Obama's tougher tone this time, compared to the Colorado shooting, when he called for "prayer and reflection."

Action speaks louder than words. If Obama wants to take practical measures to control guns, he has to make preparation for a protracted war and considerable political cost.