On Wednesday, President Obama initiated 23 executive actions designed to help combat gun violence. But as he himself acknowledged, there's only so much he can do on his own. The "most important" changes, he said, need to go through Congress.

"To make a real and lasting difference, Congress too must act," said the president. "And Congress must act soon."

There are three main actions that the president wants Congress to take. The first is to mandate background checks for anyone who wants to buy a gun. (Right now, gun buyers who want to avoid background checks can, for instance, purchase a gun from a private seller at a gun show.) The second is to reinstate the ban on military-style assault weapons and limit ammunition magazines to 10 rounds. And the third is to confirm Todd Jones as director of the Bureau of Alcohol, Tobacco, Firearms and Explosives. Congress has not confirmed an ATF director in six years, and the president argued that doing so would improve the ability of that organization to help law enforcement in combating gun violence.

The president is also calling on Congress to ban armor-piercing bullets and pass new gun trafficking laws, pass his $4 billion plan that would provide funding for 15,000 police officers, and "end the freeze" on funding public health research on gun violence.

Senate Majority Leader Harry Reid, D-Nev., said soon after Mr. Obama's remarks that he is "committed to ensuring that the Senate will consider legislation that addresses gun violence and other aspects of violence in our society early this year." Democratic lawmakers plan to introduce an "updated" bill to ban assault weapons and high-capacity magazines on January 24, and the Senate Judiciary Committee plans to hold its first hearing on the proposals on January 30.

Getting the 60 votes necessary to overcome a filibuster and pass a bill in the Democrat-led Senate won't be easy: The vast majority of Republicans as well as a minority of Democrats (mostly from the West and South) have traditionally been averse to new gun control legislation, and while some have softened their stance in the wake of the Newtown massacre, there remains considerable skepticism around passing what would be the most ambitious gun control legislation in decades.

"I will fight proposals in the Senate that threaten our Second Amendment rights and fail to take real action to curb a culture of gun violence in America," Pat Roberts, R-Kan., said Wednesday. "I fully support enforcing the gun laws currently on the books instead of creating new ones that erode basic rights of self-protection." Added Sen. Charles Grassley, R-Iowa: "The President seems to think that the Second Amendment can be tossed aside."

Getting the plan through the Senate is the (relatively) easy part. There is even more opposition in the GOP-led House, where Speaker John Boehner, R-Ohio, could simply refuse to bring the proposal up for a vote. (Boehner spokesman Michael Steel said Wednesday that House committees will review the president's plan, "[a]nd if the Senate passes a bill, we will also take a look at that.") Many conservative House Republicans have already made clear they have no interest in passing the president's plan.