When Trent Lott represented Mississippi in the U.S. House and later, during his 18 years in the U.S. Senate, his colleagues, when asked about Lott, would invariably respond, “He knows how to count votes.”

Different legislators bring different skills to the process. Some are negotiators, some are forceful speakers, some have deep, topical knowledge. Lott’s attribute was gauging the political landscape. He sensed what would fly and what would die. That talent is essential to mastering the ins and outs of expending or saving political capital. It moved Lott right up the ladder to majority leader when Republicans controlled the Senate. How good was he? To date, Lott is the only person to have served as party whip in both chambers of Congress.

In the weeks ahead, Americans will get a clear illustration of what happens when federal lawmakers get into a showdown between policy and party.

Here’s what that means:

• U.S. Rep. Bennie C. Thompson, the tenured Democrat who represents Mississippi’s 2nd Congressional District, will vote for any health bill the leadership gets to the floor. As sure as summers in the South mean sunny days, Thompson is an “aye.” Period. End of discussion.

• Likewise, although he doesn’t have nearly as long a record, it’s a sure thing that U.S. Rep. Gregg Harper, a freshman Republican from Mississippi’s 3rd Congressional District will vote “no.”

Nothing short of a divine intervention will change that alignment. What’s in the bill or what’s not in the bill, what voters want or don’t want — the policy aspects — don’t matter. Thompson and Harper are so far apart in their philosophies that there really is no middle ground.

Thompson’s record shows him voting “aye” when 44 other House Democrats broke ranks on the energy “cap and trade” bill earlier this year. It’s clear enough that cap and trade, if passed by the Senate, will raise the cost of every smidgen of energy purchased by residents of Thompson’s district, already one of the most impoverished in America. But the party line was “aye” and “aye” is how Thompson voted.

Harper is really yet to be tested, but he started out as a party man and there’s no reason to believe he’ll change.

Mississippi’s other two delegates to the House, Rep. Travis Childers of District 1 and Rep. Gene Taylor of District 4, both Democrats, are different. The generic label applied to them is “blue dogs,” members of a coalition of moderate to conservative Democrats who will, on occasion, invite the displeasure of House Speaker Nancy Pelosi, D-Calif., by voting with Republicans. Childers and Taylor, for example, both voted against cap and trade.

Both blue dogs from Mississippi are on record opposing the health reform bill expected to be voted on in the House after the recess. They come to that position differently.

Taylor, in the House for 20 years, is his own man. He always has been and his constituents like it. He’s known for weighing legislation and casting his vote independently. His position on healthcare is pretty straightforward: It could be better, but given the size of the existing federal deficit, he says now’s not the time to strap on up to $1 trillion in new debt. So that’s that.

Childers, like Harper, is a newbie. Further, he was something of a surprise winner in May 2008 special election voting after former Rep. Roger Wicker, a Republican, moved to the Senate. Childers is also on record saying he hopes he will ultimately be able to vote on a health reform bill he can support.

Childers needs the support of the Democratic Party if he expects to win re-election in 2010 because Republicans are sure to mount an all-out effort to reclaim the seat. But he well knows most of his constituents are conservative.

Voting day on health reform will not make or break the political careers of Thompson, Harper or Taylor. Childers, however, who less than two years ago was filing deeds as chancery clerk of Prentiss County, is in the hottest of hot seats — and it could get hotter.

The cap and trade vote was 219 to 212 with eight Republicans and 211 Democrats voting “aye,” three members not voting and one open seat. A strict party-line vote on the health bill would be 256 Democrats for and 178 Republicans against. If Republicans vote as a bloc, it would take exactly 40 blue dogs to kill the legislation.

That’s really not many, given the 44 defections on cap and trade.

So not just his political future, but the future of health care services in America could well be on the line with a single vote and it could be the vote of Travis Childers.

Trent Lott might be able to call how this will go. Few others could.