Is this child-like or what?

They work in the same building. They slog through the same rigorous travel schedule. Along the way, they often cross paths several times a day.

But Senators Hillary Rodham Clinton and Barack Obama have barely spoken to one another – at least in any meaningful way – for months.

The tension between the two Democratic presidential hopefuls, which spilled over into public view during the past two weeks, has been intensifying since January. It is clear, as the candidates approach a mid-point in their fight for the nomination, that the genteel decorum of the Senate has given way to the go-for-the-jugular instinct of the campaign trail.

As the Senate held an unusually late session of back-to-back votes on Thursday evening, the two rivals kept a careful eye on one another as they moved across the Senate floor.

For more than two hours, often while standing only a few feet apart, Mrs. Clinton and Mr. Obama never approached one another or exchanged so much as a pleasantry. In the clubby confines of the Senate, even the fiercest adversaries are apt to engage in the legislative equivalent of cocktail party chit-chat.

The relationship began to change, according to several Democrats who are friendly to both senators, when Mr. Obama began musing aloud about a presidential bid. The day he opened his exploratory committee, several Senate observers said, he extended his hand and said hello on the Senate floor. She breezed by him, offering a cool stare.

One week later, following the State of the Union address, the two senators found themselves doing a back-to-back interview on CNN. Mr. Obama went first, with Mrs. Clinton pacing a few feet away. Finally, an aide escorted her completely around the rotunda of the Russell Senate Office Building, avoiding walking directly by Mr. Obama.

The Senate is known for its clubby atmosphere. Even senators from opposing parties banter and have fun while votes are being counted. I’ve seen it hundreds of times on TV.

So what’s with these two? This is an example of why our nation is being torn asunder. Grow up, Senators, the world is watching you both.