The troops hit the ground last week.

Now the commanders-in-chief (or maybe better stated would-be commanders-in-chief) are landing.

Get used to it. For the next six weeks, Hillary Clinton and Barack Obama are going to be our new neighbors.

That’s because, at least for Democrats, Pennsylvania is now the center of the political world. The Keystone State goes to the polls April 22, with a crucial chunk of delegates up for grabs.

Hillary Clinton kicked off her Pennsylvania campaign in her father’s home town of Scranton last night. Tonight she will hold a rally on the Temple University campus in Philadelphia.

Barack Obama is due in Bucks County for an event today. We’re hearing rumblings of an event Wednesday night in Springfield to open a campaign office.

It’s only a matter of time before both candidates put in some serious face time in Delaware County.

Lest we forget, that is only one side of the story. How could we forget Republicans here in Delaware County?

Luckily, Arizona Sen. John McCain will be here this week to remind us that, as much fun as it is to see two Democrats slugging it out against each other, that’s only half the equation.

The presumptive GOP nominee will hold a town hall rally Friday at Springfield Country Club. He’s due to speak for about an hour.

But the spotlight, at least for the next six weeks, is going to focus on the Democrats.

Obama vs. Clinton has the makings of one of those steel-cage matches. Clinton yesterday floated the idea that she likely would welcome Obama as her running mate.

It was not exactly well-received by the senator from Illinois. He pointed out that since when does the candidate in second place offer the VP position to the leader in the clubhouse?

He’s right about that. He has more delegates, more popular votes, and has won more primaries and caucuses.

But it’s where he’s won – and where Clinton has won – that creates problems for his argument.

Clinton has been the winner in big states, like California, Michigan, Texas and Ohio. Those are the states Democrats will need to carry in November to win back the White House.

Her campaign points out that many of the states won by Obama will be captured by the Republicans in November.

Neither side appears ready to blink in this face-off.

The only face with a smile on it belongs to the guy who will be here on Friday.

Forgive John McCain if he wears a grin like a cheshire cat. He can stay out of the fray, sort out who he wants as a running mate, put together his team for the fall, and most importantly raise money, while Democrats spend millions scratching each others’ eyes out.

It’s hard not to believe that the “winner” of this Democratic donnybrook could be anything but.

Still, I wouldn’t look for Democrats to unite anytime soon. At least not in the next six weeks. We’re going to have a ringside seat for this one.

Brace yourself. This is only Round One.