President Barack Obama laid the groundwork Friday for his last year in office, vowing not to fade into the background but instead to "leave it all out on the field'' in 2016.
During a wide-ranging year-end news conference, Obama touted big wins for his administration, citing job growth, diplomacy with Iran and Cuba, the passage of significant climate and Asia-Pacific trade deals, a Supreme Court ruling legalizing gay marriage and a congressional rewrite of the No Child Left Behind law.
He also noted that nearly 6 million people have been able to sign up for coverage under his health care law so far this year.
However, the president also said several challenges remained, the main one being the growing threat of the Islamic State group and the possibility of lone-wolf terror attacks at home, like the recent mass shooting in San Bernardino, California.
Obama stressed the need to remain vigilant in the United States even as his administration works with the international community to squeeze IS.
"Squeezing ISIL's heart, its core in Syria and Iraq, will make it harder for them to pump their terror and propaganda to the rest of the world," Obama said, using an acronym for the militant Islamist group.
“Now, they are going to continue to be dangerous,” he added. "All of us can do our part by staying vigilant, by saying something if we see something that is suspicious, by refusing to be terrorized and by staying united as one American family."
But analyst Anthony Cordesman with the Central for Strategic & International Studies does not foresee improvement in 2016.
“We’re talking about a series of wars and violent movements throughout much of the Islamic world. Even if we could defeat ISIS tomorrow, by all the stats we have on terrorism, at least two-thirds of that volume of terrorism would go on because it’s driven by other movements,” he said, using another Islamic State acronym.
Amid widespread fears about terrorism and extremists, Obama pushed back against critics questioning his strategy for overcoming the Islamic State group in Iraq and Syria. "There's only so much bombing you can do," he said.
However, he said, "We're going to defeat ISIS, and we're going to do so by systematically squeezing them, cutting off their supply lines, cutting off their financing, taking out their leadership, taking out their forces, taking out their infrastructure."
Visa review process
On Thursday, U.S. lawmakers criticized the visa review process for people seeking to enter the United States.
Obama said Friday that law enforcement and intelligence officials were looking for ways to better monitor the public communication of suspected terrorists. He said he thought the U.S. had struck the right balance in protecting civil liberties while ensuring Americans' safety.
But he also warned that there were limits to what law enforcement could do.
No government is going to have the ability to "read every person's text or email or social media, if it's not posted publicly," Obama said.
U.S. President Barack Obama holds his end of the year news conference at the White House in Washington, Dec. 18, 2015.
Regarding the Syrian conflict, Obama said President Bashar al-Assad "is going to have to leave in order for the country to stop the bloodletting and for all the parties involved to be able to move forward in a nonsectarian way."
"He has lost legitimacy in the eyes of a large majority of the country," the president said of Assad.
Obama reaffirmed his determination to work with Congress to close the Guantanamo Bay detention center in Cuba.
"Guantanamo continues to be one of the key magnets for jihadi recruitment," Obama said, leaving the door open to closing the military prison by decree as a last resort.
He said the center's population would be below 100 by early next year.
WATCH: Moments from President Barack Obama's year-end news conference
The end of 2015 will mark a major transition point for Obama, who has one year left to try to complete any unfinished projects.
With America facing a general election in 2016, in which candidates are elected in all or most constituencies of a nation or state, Obama is unlikely to roll out any sweeping new policy proposals that would be unlikely to get serious consideration amid focus on the poll.
Criminal justice reform
Earlier Friday, Obama pardoned two people and commuted the sentences of 95 others in an end of year act of executive power, the White House announced.
Almost all of those receiving commuted sentences were nonviolent drug offenders. Many were convicted of distributing or possessing cocaine or crack-cocaine.
The commutations, the most Obama has issued at one time, aim to build momentum for the president's broader push on criminal justice reform.
The White House has been working with lawmakers from both parties in an effort to overhaul U.S. sentencing.
FILE - Pictures of Wednesday's shooting victims are displayed at a makeshift memorial site in San Bernardino, Calif., Dec. 7, 2015.
Later Friday, Obama was to leave for San Bernardino, California, where he plans to meet with families of the 14 victims of the recent mass shooting. Obama doesn't plan any public appearances while in California.
The California stop will be Obama's last before he travels to Hawaii to spend Christmas and New Year's with his family. Obama has vacationed in Hawaii every year since taking office.
Meanwhile, 14 of Obama's nominations for top foreign policy posts and ambassadorships were left on the cutting room floor when the Senate failed to vote on them before closing its business for the year.
Texas Republican Senator Ted Cruz, who is running for the GOP presidential nomination, has placed a blanket hold on all Obama political appointees to the State Department over what he called the "catastrophic Iranian nuclear deal."
Friday's inaction means Obama will have to resubmit the nominations after the first of the year.
Some material for this report came from AP and Reuters.
WATCH: Video of President Barack Obama's year-end news conference