I probably would stake it and use some twine or rope or something to hold it tight. I used bungee cords with some of my bareroot trees (with stakes), because they had very little roots, and the tops were very heavy... They've done great and continue to put out new growth. You could also dig it up, but its a bad time to be doing that sort of thing, especially if its actively growing.

Depending on your soil, you can water it heavily, move some soil to one side, and lean it back without uprooting it. It's easier when it's really really wet.
John S
PDX OR

Thanks for the great suggestion but I've already staked it. I purchased one of the staking kits from Lowes. I was definitely against tree staking because I think trees can do better overall if they can be exposed to the elements and forced to grow a stronger root system. But I felt like I had no other choice.

Pranksta,

What you describe is very common here with young peach trees. As long as the tree is not tilting too much I usually just leave it alone, although I do put sand in the wallowed out hole.

That brings up another point. It helps to put sand in the wallowed out hole. Peaches routinely wallow out and by pouring sand in the hole (and mounding it up around the trunk a little) it stiffens the tree up until the trunk gets big enough to stabilize the tree.

For the first couple years I have to do this for nearly all my peach trees in the springtime and early summer.

This week I just received 9T of bulk sand for my new planting, so I'm not chasing sand bagged sand all summer long to stabilize my new trees. Many of them are wallowed out and need some attention. I plan to mound up sand around each tree, whether it needs it or not.

I would never consider digging a tree up because it was leaning.