The Note's Must-Reads are a round-up of today's political headlines and stories from ABC News and the top U.S. newspapers. Posted Monday through Friday right here at www.abcnews.com

Compiled by ABC News Digital News Associates Jayce Henderson, Amanda VanAllen and Desk Assistant Nadine Selim

NEWT GINGRICH: ABC News' Elizabeth Hartfield: " Gingrich Files in Va., But Other GOP Candidates Do Not" After a great deal of speculation, former House Speaker Newt Gingrich filed his paperwork for the Virginia presidential primary with the state's board of elections in time for Thursday's 5 p.m. deadline, although several of his opponents did not. LINK

The New York Times' Trip Gabriel: " As New Gingrich Takes Center Stage, Old Reputation Lurks in Wings" Not long ago Newt Gingrich placed a call to Jack Nicklaus, the golf legend, seeking advice on how to pace himself. Mr. Nicklaus, according to the Gingrich campaign, recalled that when he was on the pro tour, it was possible to pour a lot of energy into a tournament, but impossible to sustain the effort weekly without respites. LINK

Bloomberg's Jonathan D. Salant and Julie Hirschfeld Davis: " Gingrich Challenges Romney to Debate Over Attack Ads in Iowa" Two front-runners for the Republican presidential nomination are sparring over campaign ads, with Mitt Romney saying the party's nominee will face worse in the general election and Newt Gingrich challenging him to defend the commercials in a debate.  Gingrich, a former U.S. House speaker, criticized the ad campaign being waged in Iowa by supporters of Romney through an independent political action committee. LINK

The Wall Street Journals' Patrick O'Connor and Danny Yadron: " Gingrich Rips Paul on Foreign Policy" Republican presidential candidate Newt Gingrich lashed out at rival Ron Paul Thursday, despite a promise to focus his campaign on "positive ideas," saying that Mr. Paul wasn't taking foreign threats to the U.S. and Israel seriously. The former House Speaker's criticism highlighted how Mr. Paul, a Texas congressman, has become a potent force in the Republican contest, overtaking Mr. Gingrich recently in public-opinion surveys of Iowa as the two jockey to become the leading alternative to Mitt Romney. LINK

RICK PERRY: The Washington Post's Sandhya Somashekhar: " Rick Perry back in Iowa, with less roar and more whisper" Rick Perry stormed into the Republican presidential race with a certain swagger over the summer, when he planted one foot on a hay bale at the Iowa State Fair and roared, "Government, get out of the way." LINK

MITT ROMNEY: ABC News' Emily Friedman: " Voters Ask Romney, 'Why You and Not Him?'" At the sixth and final stop of the second day of his whirlwind New Hampshire bus tour, Mitt Romney was faced with a question he's likely to hear again and again, especially if he becomes the GOP nominee. LINK

Politicos' Juana Summers: " Mitt Romney's day of N.H. hard knocks" Knock, knock. Who's there? It's Mitt Romney. The former Massachusetts governor, on the second day of an old-fashioned bus tour through New Hampshire's North Country, spent more than an hour knocking on doors here, hoping to win over a few undecided voters before the state's Jan. 10 primary. LINK

CHRIS CHRISTIE: New York Daily News' Roque Planas: " NJ Gov. Chris Christie would consider running as vice president for GOP" Chris Christie broke the hearts of many Republicans when he declined to run for president, but his GOP fans may yet see him in the White House - as the veep. LINK

RON PAUL: ABC News' Shushannah Walshe: " Ron Paul Talks 9/11, Iran, and Cookbooks On His Last Tour Stop Before Christmas" Ron Paul was greeted by adoring and large crowds throughout the day Thursday, and at his last event at a hotel he touched on one of his most controversial past comments, saying "people misinterpret what I say about what happened on 9/11." LINK

OTHER / VOTERS: The Washington Times' David Sherfinski: " Four of seven GOP hopefuls meet deadline for Virginia ballot" Four Republican presidential candidates - including former House Speaker Newt Gingrich - managed to file petitions to qualify for the GOP primary ballot in Virginia ahead of a 5 p.m. Thursday deadline. LINK

Los Angeles Times' Robin Abcarian and Seema Mehta: " Republican candidates flood Iowa with Negative ads" Reporting from Des Moines-With no snow on the ground in this unseasonably warm state, the only blizzard Iowans are facing is the daily onslaught of negative political ads as they turn on their televisions, tune in their radios or visit their mailboxes. And they aren't safe when they pick up the phone or fire up their Internet connections either.   LINK

USA Today's Richard Wolf: " Voters leaving Republican, Democratic parties in droves" More than 2.5 million voters have left the Democratic and Republican parties since the 2008 elections, while the number of independent voters continues to grow.A USA TODAY analysis of state voter registration statistics shows registered Democrats declined in 25 of the 28 states that register voters by party. Republicans dipped in 21 states, while independents increased in 18 states. LINK

ABC NEWS VIDEOS: " Romney to Beat Gingrich for Nomination?" LINK

BOOKMARKS: The Note: LINK The Must-Reads Online: LINK Top Line Webcast (12noon EST M-F): LINK ABC News Politics: LINK The Political Punch (Jake Tapper): LINK George's Bottom Line (George Stephanopoulos): LINK Follow ABC News on Twitter: LINK ABC News Mobile: LINK ABC News app on your iPhone/iPod Touch/iPad: LINK