At best, the four candidates who appeared together Tuesday are each expected to compete for single-digit percentages of the vote in the states where they will appear on the ballot.

Not one has made a showing on the national radar akin to Ross Perot in 1992, when the Texas billionaire and third-party candidate carried nearly 20 percent of the popular vote. Goode, Johnson and Stein each claimed 1 percent support in an early September Gallup poll of national adults.

But even if they attract only nominal enthusiasm, these long-shots could become entangled in the race between Romney and Obama.

Johnson will appear on the ballot in 48 states, including some key battlegrounds with independent streaks where his blend of fiscal conservatism and libertarian social views could make him a compelling alternative for conservative voters not wedded to voting for Romney.

In Colorado, New Hampshire and Nevada, in particular, Johnson could be a thorn in Romney’s side if the election is close. Johnson received just 2 percent support in a recent Suffolk University-News 7 survey of those likeliest to vote in New Hampshire.

But the poll also showed that Johnson hurt Romney more than Obama.

“Politics is full of ironies. Gary Johnson voters are predisposed to voting against the incumbent president, but Johnson’s presence on the New Hampshire presidential ballot is actually helping Obama,” said David Paleologos, director of the Suffolk University Political Research Center.

If Virginia is exceptionally close, Goode, despite attracting just 2 percent support in a mid-September Washington Post poll in that state, could be an also-ran to remember.

The Democrat-turned-Republican-turned-independent congressman — who could benefit from residual name identification in southern Virginia — threatens to steal support from Romney at the margins, potentially costing the Republican big.