Democrat Sanders seeks to upset Clinton in first two contests and then stay competitive for the long haul.

Democratic presidential hopeful Bernie Sanders is preparing for a protracted battle with Hillary Clinton by hiring staff and laying groundwork in more than a dozen contests that follow Iowa and New Hampshire, the first two nominating states.

Sanders has deployed about 50 paid campaign aides apiece to Nevada and South Carolina, the next two states on the calendar.

Paid staff are on the ground in all of the 11 "Super Tuesday" states that vote on March 2, a presence that appears to at least match that of the Clinton camp.

The Vermont senator is also airing TV ads and Spanish-language radio spots in Nevada. He is about to go on TV in South Carolina.


And his team is mapping out plans to spend a fresh wave of small-dollar donations expected to arrive if he upsets Clinton in Iowa or New Hampshire, as recent polls indicate is possible.

That money, aides say, would allow Sanders to compete with the former Secretary of State and Democratic front-runner in the crush of contests that follow on the calendar, as the playing field rapidly broadens and the election becomes more dependent on expensive television ads.

The preparations are part of an effort to buck the latest conventional wisdom surrounding the Democratic contest: that even if Clinton loses the first two contests, her superior campaign infrastructure and other advantages, including the demographics of the electorate, will allow her to crush Sanders in subsequent states.

"There will absolutely be a very active contest after the first two states," said Sanders's campaign manager, Jeff Weaver, who disputed the oft-repeated notion that Clinton has a "firewall" in states that follow Iowa and New Hampshire.

Clinton's advisers say they also have paid staff in all March 2 states, but they declined to share numbers.

Aides also noted that Clinton has made at least one stop in each of the Super Tuesday states, with the exception of Vermont.

"Knowing this race would always tighten, our campaign has been building a strong grassroots organisation since day one," Clinton spokesman Jesse Ferguson said.

Despite the fresh preparations, Sanders, who represents a state that is 95 per cent white, continues to trail Clinton among Hispanic and African American voters, who make up large shares of the Democratic electorate in Nevada, South Carolina and many of the March 2 states.


Clinton has led in the few polls that have come out of Nevada, and she has held a commanding average margin of about 40 percentage points in South Carolina, largely on the strength of African American voters.

Several other Southern states would seem to favour Clinton because of the sizable African American populations, including Arkansas, Georgia, Texas and Virginia. Sanders is simply not known by many black voters.

Aware of such challenges, Sanders has been, and plans to continue, making appearances in several March 2 states. On Tuesday, he drew a crowd of more than 7000 in Birmingham, Alabama.

Sanders is counting on a shift in momentum that will alter the dynamics in subsequent states if he wins Iowa and New Hampshire.

"If Sanders beats Clinton in the first two states, there will be a very, very strong narrative about his momentum, and then who knows what happens," said Mo Elleithee of Georgetown University.

He said Clinton is in a better position to rebound than she was during her 2008 presidential bid.


Sanders has nearly matched Clinton in fundraising during the past two quarters. But Sanders' aides argue they are better positioned because the vast majority of their donors have not yet given the legal maximum of US$2700.

The Sanders team points to South Carolina, where Barack Obama trailed Clinton in 2008 polls until after Obama beat her in Iowa.

The vote in South Carolina will be influenced in part by the states before it, said Jamie Harrison, chairman of the South Carolina Democratic Party. "It's all about momentum and building it."

Looking ahead
The Democrat nomination timetable next month:
• Feb 2 Iowa caucuses
• Feb 10 New Hampshire primary
• Feb 21 Nevada caucuses
• Feb 28 South Carolina primary *All NZ day times