I don't usually post unsolicited advice to the Obama campaign, because they haven't needed it. They have a game plan, they don't panic and tear it up when they hit bumps in the road. And they are the campaign still on route to the nomination.

But since everyone is running on fumes at this point, perhaps some outside advice is worthwhile.

The campaign appears to realize it's time for a tweak. Today's NYT headline is: "Obama Shifting Focus From Clinton to McCain."

But how should they shift?

Obama's greatest weapon is his speech. It's how he can demand attention, paint big themes, frame the debate and drive media coverage.

It's time for a speech, or speeches, drawing a stark contrast with McCain around big themes. Not just a one-off speech, but something that would lay the groundwork for the fall campaign.

For example, McCain is trotting out the usual "big government" attacks on both Obama and Clinton.

Why not take that head on?

Why not deliver a major speech outlining Obama's vision for a representative, responsive, responsible government that's an agent of progressive change, contrasting it with McCain's incoherent attempt to appeal to anti-government conservatism and desperate-for-active -government moderates?

Taking on the question of the role of government -- something Dems have run from for so long -- is bound to attract attention.

If he nails it like his speech on race relations, he will crystallize what he will do to get our economy back on track, and further show he can run circles around McCain in the general election.

Or he could deliver a major speech on global warming, insisting that the current Lieberman-Warner bill being considered in the Senate falls short of what's needed, and laying out a plan that will ensure the 80% cut in greenhouse has emissions needed by 2050.

Or he could deliver another foreign policy speech that directly attacks neoconservatism and makes clear McCain is offering more of it.

The key is to give a speech that offers more than uplifting inspirational rhetoric, but isn't so dense that the media doesn't bother with the details and ends up ignoring it.

If he hits the sweet spot, the right balance of inspiration and substance, he'll once again make inroads into Clinton's support, and position himself well for the general election.