First Thoughts: An explicit call to action Evan Vucci / AP President Barack Obama pauses as he delivers a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. Obama makes an explicit call to action after Newtown shootings... But will there be follow-through?... Breakthrough on fiscal cliff... The president's cabinet announcements might not come this week... Hillary Clinton faints, will miss this week's Benghazi hearing... And Nikki Haley set to announce pick to fill Jim DeMint's Senate seat. An explicit call to action: Unlike his past remarks after other tragic shootings, President Obama last night made an explicit call to action when he addressed thousands who were grieving in Newtown, CT. We can't tolerate this anymore. And to end them, we must change," Obama said. We will be told that the causes of such violence are complex, and that is true. No single law -- no set of laws can eliminate evil from the world, or prevent every senseless act of violence in our society. He added, "But that can't be an excuse for inaction. Surely, we can do better than this. If there is even one step we can take to save another child, or another parent, or another town, from the grief that has visited Tucson, and Aurora, and Oak Creek, and Newtown, and communities from Columbine to Blacksburg before that -- then surely we have an obligation to try. Much like George W. Bush's remarks following 9/11, Obama's speech attempted to both mourn and galvanize. And he spoke as a parent and a frustrated American. It may be one of the most important speeches Barack Obama will give as president (depending on what happens next, of course). But will there be follow-through? The president's speech, however, didn't offer any details of what he'd like to try to end future tragedies. But the Wall Street Journal, speaking to two administration officials, gets an outline of what the White House is possibly considering. One possibility likely to be considered is a ban on high-capacity magazines, the devices attached to firearms that store large numbers of bullets and reload them rapidly. Meanwhile, on "Meet the Press" yesterday, Sen. Dianne Feinstein said she will introduce legislation at the beginning of the next Congress to ban assault weapons. It will ban the sale, the transfer, the importation and the possession. Not retroactively but prospectively. And it will ban the same for big clips, drums or strips of more than 10 bullets. So there will be a bill. And even Sen. Joe Manchin, on "Morning Joe" today, said: "Everything should be on the table." But the question is follow-through. It's one thing for politicians to make calls for action in the hours after a tragedy; it's another thing for them to follow through with it weeks -- or months -- later. The Daily Rundown's Chuck Todd talks about the latest in the Sandy Hook Elementary School rampage. And on what issues? So Obama and others have raised expectations. Can they deliver? To pull this off in the gun area, the president is going to have to tackle every issue associated with these heinous crimes: gun laws, our gun culture, mental health, the de-sensitization of violence thanks to Hollywood and video game makers, and of course parental responsibility. If it's a LARGER policy discussion, it's much harder for the most ardent NRA-supporting lawmaker to walk away. The fiscal cliff talks between the president and House Speaker John Boehner have seen some movement, with the Republican leader showing some willingness to budge on the president's demand for tax increases on the wealthiest Americans. NBC's Kelly O'Donnell reports. Fiscal-cliff breakthrough: Friday's tragedy in Connecticut also has had this immediate effect -- it has made the debate over the so-called fiscal cliff seem so small by comparison. But there has been an important breakthrough in the negotiations. Per NBC's Mike Viqueira, House Speaker John Boehner has proposed raising tax rates on income of $1 million or more, and Republicans have upped their revenue target from $800 billion to around $1 trillion. The White House, of course, wants rates to increase for income above $250,000, but now there's the possibility the ultimate line will be somewhere in between $250,000 and $1 million. For their part, Viqueira adds, Democrats will move beyond their $600 billion proposed savings on entitlements. The overall number could be closer to the Republican revenue number on revenues of $1 trillion - or maybe just a tad under. The last administration number was $600 billion. What's more, both sides would agree to broad tax and entitlement reform by Fall 2013 (with more triggers), and they would raise the debt ceiling to last until the end of next year. Nothing is set in stone, but there's certainly more optimism in getting a deal than there was at the end of last week. The question worth pondering: Does what happened in Connecticut give both sides more room to negotiate and for lawmakers to swallow hard and cast a difficult vote? Cabinet announcements might not come this week: After Susan Rice withdrew her name from consideration last week, the writing on the wall is that Obama will tap John Kerry as his next secretary of state. But that announcement might not happen this week. The New York Times: "President Obama is leaning strongly toward naming John Kerry, the Massachusetts senator and unsuccessful Democratic nominee for president eight years ago, to succeed Hillary Rodham Clinton as secretary of state, according to administration officials and friends of Mr. Kerry. But the announcement will be delayed, at least until later this week and maybe beyond, because of the Connecticut school shooting and what one official called "some discomfort" with the idea of Mr. Obama's announcing a national security team in which the top posts are almost exclusively held by white men." We can tell you that the concerns about diversity -- or a lack thereof -- are real. U.S. Secretary of State Hillary Clinton fainted from apparent dehydration and suffered a concussion in the incident, according to officials. Clinton faints, will miss Benghazi hearing: As for Hillary Clinton, we learned over the weekend that -- due to illness -- she fainted last week and sustained a concussion in the process. And as a result, she won't be testifying at Thursday's congressional hearing on Benghazi. We do wonder if there will be any pressure on her to testify at a later date. Indeed, GOP Rep. Ileana Ros-Lehtinen released this statement on Saturday: "We have been combing through classified and unclassified documents and have tough questions about State Department threat assessments and decision-making on Benghazi. This requires a public appearance by the Secretary of State herself. Haley set to announce her pick: Finally, South Carolina Gov. Nikki Haley (R) will announce her pick to fill Sen. Jim DeMint's (R) Senate seat at noon ET today, her spokesman said earlier this morning. As NBC's Ali Weinberg reported last week, these Haley's five finalists: U.S. Rep. Tim Scott, U.S. Rep. Trey Gowdy, former state Attorney General Henry McMaster, former South Carolina First Lady Jenny Sanford, and Catherine Templeton, who heads state Department of Health and Environmental Control.