For Hillary, it’s back to the scene of the crime – Iowa: This afternoon, Hillary Clinton holds her first official campaign event in Iowa, where she finished third in 2008. As of one us writes, “Last time, Iowa was the beginning of the end for Hillary Clinton… Now, she’s returning to the state that plagued her nearly eight years ago to again make her case to Democrats and to the country that she’s the candidate who can best represent the famously meticulous voters of Iowa.” Today’s event is a roundtable with educators and students at 2:15 pm ET in Monticello. Tomorrow’s is a small-business roundtable in Norwalk. Both are small towns, and you can tell a candidate who’s trying to win Iowa by how many times they visit small towns in the Hawkeye State vs. Des Moines. (Just ask Rick Santorum, the GOP’s 2012 winner.) The questions we have for Hillary: How comfortable will she be? How will she handled shouted questions from the press? And will she actually try and show something of where she stands on key issues?

Rubio turns a lemon into lemonade: Yes, Hillary Clinton campaign start stepped on Marco Rubio’s presidential announcement yesterday. But Rubio was able to use Clinton in the news to make a contrast with her – and also, by extension, Jeb Bush. “Just yesterday, a leader from yesterday began a campaign for president by promising to take us back to yesterday,” he said of Clinton without mentioning her name. “But yesterday is over, and we are never going back.” More: “Before us now is the opportunity to author the greatest chapter yet in the amazing story of America. We can’t do that by going back to the leaders and ideas of the past. We must change the decisions we are making by changing the people who are making them.” And: “At the turn of the 19th century, a generation of Americans harnessed the power of the Industrial Age and transformed this country into the leading economy in the world. And the 20th century became the American Century. Now, the time has come for our generation to lead the way toward a new American Century.” Whether it’s Rubio, Walker, Paul, or Cruz, the GOP candidates using this past-vs.-future punching bag against Hillary also will be hitting Jeb Bush, too. You get two hits for the price of one. As for Rubio’s speech, it was a solid performance. But you could also tell he was nervous. Then again, who wouldn’t be nervous?

Biography vs. policy: But here’s a question worth pondering when it comes to this generational fight: What matters more to the new generation of American voters – biography or policy? After all, polls show that two of the biggest issues for millennials are combating climate change and supporting gay marriage, both of which Rubio opposes. Indeed, check out this age breakdown on supporting same-sex marriage from our March NBC/WSJ poll:

18-34: 74% favor, 20% oppose

34-49: 54% favor, 34% oppose

50-64: 55% favor, 37% oppose

65+: 45% favor, 46% oppose

So policy is a challenge here for Rubio. Remember, both JFK and Obama tapped into a new generation of American voters not just because they were young, but also because their policies spoke to this generation. On the flip side, Hillary’s challenge will be biography. As we wrote yesterday, since 1992 (with just one exception), the winner of the general election has always been the youngest candidate.

Rubio on “Today”: On the “Today” Show this morning, NBC’s Matt Lauer asked Rubio a few questions. Here were his answers:

On the argument that he has the same level of experience as Barack Obama did in 2007: Replied that, unlike Obama, he served as Florida House speaker and will have completed a full Senate term by the time of the next presidential inauguration

On his relationship with Jeb Bush: Said that they’re still friends. But: “I just honestly believe that at this moment in our history, we need to move in a new direction as a country.”

On potentially being the nation’s first Latino president: Said it would be an honor and a sign of America’s diversity.

Christie’s Hail Mary on Social Security: Meanwhile, New Jersey Gov. Chris Christie – remember him? – is in New Hampshire today, where he’s throwing a long ball on reforming Social Security. Per his expected remarks, he will call for means-testing Social Security, including eliminating it for Americans who have $200,000 in other income. “Do we really believe that the wealthiest Americans need to take from younger, hard-working Americans to receive what, for most of them, is a modest monthly social security check? I propose a modest means test that only affects those with non-social security income of over $80,000 per year, and phases out social security payments entirely for those that have $200,000 a year of other income,” Christie is expected to say. He’ll also call for raising Social Security’s retirement age to 69, raising Medicare’s eligibility age to 67 by 2040; and eliminating the payroll tax for seniors who stay in the workforce past the age of 62. Here’s the thing about Social Security: It wins you lots of style points with conservative intellectuals. But it’s increasingly risky for Republicans to talk about this, given that their base is white seniors. Remember when Greg Walden, chair of the House GOP’s campaign arm, attacked Obama’s chained CPI proposal on Social Security? The reason: Changing/reforming/restructuring it is TOUGH politics.

OFF TO THE RACES: Rubio’s “Day One”

Team Rubio is selling special “Day One” swag on MarcoRubio.com today for those hoping to bank the proof that they were his earliest backers.

RUBIO: NBC’s Andrew Rafferty wraps Rubio’s announcement: “Florida Senator Marco Rubio declared “yesterday is over” and pledged to lead the country into a “new American Century” of prosperity when he began his presidential run in Miami on Monday.”

And our Perry Bacon Jr. delves into Rubio’s rise to power in the Florida House.

Here’s his interview with MSNBC’s Kasie Hunt.

Rubio, asked about Jeb Bush on TODAY: “”I just honestly believe that at this moment in our history, we need to move in a new direction as a country.”

Rubio in USA Today: It’s time to revive Lincoln’s “One Country, One Destiny.”

The Atlantic asks if it’s Rubio’s time. “American presidential politics now is less determined by party; more by personal appeal, advocacy groups, ideologically fueled money, and extra-party vote-getting machinery. This is the context that made 2008 Obama’s Time, and may now make 2016 Rubio’s Time.”

He told ABC that he’d keep Guantanamo Bay prison open – and grow it.

And he told NPR that he’s “very confident” and ready to be president “on Day One.”

“Sen. Marco Rubio has been cultivating a relationship with Mitt Romney and his intimates, landing some of the 2012 Republican nominee’s top advisers and donors and persistently courting others as he readies an expected 2016 presidential campaign,” writes the Washington Post.

The Des Moines Register: “U.S. Sen. Marco Rubio’s race to the White House will run through Iowa, but his stand on immigration and his parallels to another young senator who ran for president could present obstacles in the first-in-the-nation caucus state, Republican activists said.”

CLINTON: If you’re dying for the details of Clinton’s Chipotle stop, we got you covered.

She’s kicking off her Iowa campaign with a low-key event in Monticello. Also, per the AP: “Advisers have set a modest goal of raising $100 million for the primary campaign and will not initially accept donations for the general election.”

Ruth Marcus calls her kickoff video “vapid.”

Patrick Healy writes in the New York Times: “On one side is a crowd of Republicans trying to look presidential. On the other side is a lone Democrat trying to look normal.”

POLITICO reports that Republicans are rallying around a plan of attack against Hillary Clinton “rooted in her accumulation of wealth and designed to frame her as removed from the concerns of average Americans.”

Also from POLITICO: “The former secretary of state isn’t naming a finance chair in her latest bid for the White House, according to several sources close to her campaign. The move is part of a larger strategy of trying to maintain a nimble campaign structure and avoid the mistakes of her 2008 bid when she was criticized for building out a massive and overpaid staff.”

CARSON: Dr. Ben Carson will announce his presidential bid on May 4 in Detroit, one of us writes.

CHRISTIE: People in New Jersey are even MORE sour on Chris Christie than they were earlier this year. A new poll finds nearly 70 percent of registered voters in the state say he wouldn’t make a good president.

The Asbury Park Press previews the entitlements plan he’ll be pitching today.

Yahoo’s Matt Bai has an extended interview with Chris Christie, who says he’s ready to run for president now but wasn’t in 2012. (Timing’s everything, right?)

KASICH: He’s saying he’s “seriously considering” a run.

And around the country…

ARIZONA: Looks like John McCain is getting a primary from State Sen. Kelly Ward.

MASSACHUSETTS: So much for those who thought Deval Patrick was heading straight for national politics. “The former governor of Massachusetts, Deval Patrick, has joined the private equity firm Bain Capital as a partner to focus on socially oriented investments, a person briefed on the matter said on Monday.”

OBAMA AGENDA: Negotiating into the night

The New York Times: “Leaders of the Senate Foreign Relations Committee negotiated into the night on Monday to soften language and possibly shorten a congressional review period in legislation that would give Congress influence over the shape of President Obama’s nuclear accord with Iran.”

From the Washington Post: President Obama’s quest to get a deal with Iran on its nuclear program hinges on not only reaching across the aisle in Congress but also across oceans to find common ground with enemies. That strategy — which links two themes that have dominated his presidency, a yearning for post-partisan politics and a belief in engagement — receives a new test Tuesday as the Senate Foreign Relations Committee begins debate on a bill that would severely restrict Obama’s ability to cut a nuclear arms deal with Iran.”

The Iraqi prime minister is here in Washington, looking for billions of dollars in loans and aid.

Reuters: “Iran’s Foreign Minister Mohammad Javad Zarif said nuclear talks between Iran and the P5+1 group of countries would resume on April 21, the semi-official Tasnim news agency reported on Tuesday.”

Carrie Dann contributed reporting to this article.