President Barack Obama will unveil a plan to curb gun violence, and is expected to renew the assault weapon ban.
Acting swiftly on the heels of the Newtown school massacre, Mr Obama is expected to ban military-style assault weapons and high-capacity ammunition clips, and to enact more than a dozen executive orders to get around Congressional opposition to gun control.
Vice President Joe Biden, who Mr Obama directed to lead a panel tasked with creating the proposals, will join the president at the White House on Wednesday morning to announce the measures.
"The president and the vice president will hold an event here at the White House to unveil a package of concrete proposals to reduce gun violence and prevent future tragedies like the one in Newtown, Connecticut," White House spokesman Jay Carney said.
Mr Carney said several school children who wrote letters to the president calling for tougher gun restrictions after the shooting at Sandy Hook Elementary will accompany Mr Obama and Mr Biden.
The Obama administration has been moving quickly on the issue following last month's massacre, which Mr Obama has called the worst day of his presidency.
But opposition has strengthened among pro-gun groups and Americans who fear their weapons will be taken away. The US has the highest rate of gun ownership of any country in the world.
Mr Obama acknowledged a tough fight ahead in a deeply divided Congress, whose support would be needed to pass the most sweeping changes under consideration, including background checks for anyone seeking to purchase a gun.
Such changes "make sense," Mr Obama said. Lawmakers will have to "examine their own conscience" in the debate ahead, he added.
But the gun issue will have to compete for Congress' time in coming weeks with several looming fiscal issues, and Republican leaders have said action on guns will have to wait.
The president also can use his executive powers to make some changes, and congressional officials say he is considering 19 steps that he could enact without approval from Congress.
The plan's most contentious elements face intense opposition from the influential National Rifle Association, which enjoys strong support from Republicans as well as several Democrats, and is known to punish politicians who stray from its point of view.
The assault weapons ban, which Mr Obama has long supported, is expected to face the toughest opposition in Congress, which passed a 10-year ban on the high-grade, military-style weapons in 1994.
Supporters did not have the votes to renew it once it expired.
As the president spoke on Monday, some parents who lost children in the Connecticut shooting one month ago spoke out for the first time, calling for a national dialogue to help prevent similar tragedies.
"We want the ... shootings to be recalled as the turning point where we brought our community and communities across the nation together and set a real course for change," said Tom Bittman, a co-founder of Sandy Hook Promise group.
States and cities have been moving against gun violence as well. In New York, Governor Andrew Cuomo on Tuesday signed into law the most restrictive gun law in the nation.
"This is a scourge on society," Gov Cuomo said. "At what point do you say, 'No more innocent loss of life?'"
The New York bill had bipartisan support, with the leader of the Republican-held state Senate saying it does not infringe on the Second Amendment of the US Constitution, which guarantees the right of citizens to bear arms.
At the national level, advocacy groups have also been pushing Mr Obama to order the Justice Department to crack down on those who lie on background checks - only a tiny number are now prosecuted.
Such a step has support from the NRA, which has consistently argued that existing laws must be enforced before new ones are considered.
The president's proposals are also expected to include steps for improving school safety and mental health care, as well as recommendations for addressing violence in entertainment and video games.