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Kentucky Sen. Rand Paul is criticizing New Jersey Gov. Chris Christie. Christie is suggesting other Republicans don’t understand how to win as he does.

Wisconsin Gov. Scott Walker says anyone who works in Washington, which would include Paul, should not be on the Republican ticket in 2016.

And there’s the Democrats.

While Republicans remain divided about who should be their candidates for the future, the Democrats are incredibly unified around a single person, one who is not an incumbent or the sitting vice president. Hillary Clinton has not officially said she will even run for president, but a broad coalition of groups and key party figures are pushing her to run, touting her ability to win in 2016, pledging support  and sending an unsubtle signal that other potential candidates, even Vice President Biden, should stand down if Clinton chooses to wage a second presidential campaign.

More than two years before voters will cast ballots in presidential primaries, Democratic officials say an informal apparatus for a Clinton campaign has been set up, some of which could immediately fold into a “Clinton for President” operation if she announces her candidacy. A newly-formed group called “Ready for Hillary” is seeking out the endorsements of elected officials, celebrities and key figures in important states for Clinton and building a national list of Americans across the country who could canvass for Clinton or give her a small campaign donation. Emily’s List, which promotes female Democratic candidates, is expected to do polling and research in support of Clinton. A group called “Correct the Record” that started this month will defend potential Democratic presidential candidates, including Clinton of course, against Republican attacks. Priorities USA, which ran ads backing Obama in 2012, is being organized to play a similar role for Clinton.

President Obama and the White House have not promoted  all of this pro-Hillary activity, but they are sending any signals to stop it either. Jim Messina, who ran Obama’s 2012 campaign, is in talks to take on a role with Priorities USA, Buzzfeed reported last week. Other ex-Obama aides are advising Ready for Hillary. Key Obama supporters from 2008, such as Missouri Sen. Claire McCaskill and DreamWorks’ Jeffrey Katzenberg, are now strongly behind Clinton.

“When she announces, for the first time I can remember when we have an open seat for the presidency, we won’t have a primary and she will be the consensus choice,” McCaskill said in a speech in Cedar Rapids Iowa this weekend, according to the Waterloo-Cedar Falls Courier.

One Democrat who has been rumored as a potential presidential candidate, New York Sen. Kirsten Gillibrand, said Sunday on ABC’s This Week, “I am on the bandwagon for Hillary Clinton in 2016.”

McCaskill’s comment in particular was telling. President Obama’s poll numbers are falling and if that continues, it will create a major challenge for a 2016 Democratic presidential candidate, who will be cast by the GOP as effectively running for the third term of Barack Obama.

One advantage Democrats could have, as McCaskill was alluding to, is if they spend 2015 and 2016 touting a single candidate, while Republicans are in a long, drawn-out primary that divides their Tea Party and establishment swings. (To be sure, the extended, divisive Obama-Clinton primary did not hurt Democrats in 2008.)

Another Democrat is likely to challenge Clinton for the nomination, in part because of all of the benefits of running for president even if you lose. (Increased fame because of the televised debates, an chance to promote your pet causes to a broader audience. (See Cain, Herman or Huckabee, Mike.) But if Clinton continues to accrue endorsements from establishment figures, pledges from ex-Obama aides to support her and financial commitments from major party donors, a credible rival to her, like Obama in 2008, may not emerge.

A true challenger, even if they are a popular figure like Massachusetts Sen. Elizabeth Warren, must have an infrastructure of staff, money and political support; otherwise they are running a long-shot campaign.