If your partner can arrange to have a job waiting for him (starting within 3 months of the move) in the UK making £18,600pa (more if any children are not UKC and will also need a visa) and he has made at least £18,600 in the last 12 months in the US, then you can apply on the basis of his income and pending UK employment.
Another option is relying on savings you and/or your partner have held for at least six months. The minimum savings would need to be £62,500 (which, coincidentally is 2.5 x 18,600 + 16000). You would need to have had at least that much in your accounts for a full six months before you apply... if your balance dropped below it for even one day, or if you're even one day short of six months, your visa would be refused. If you have owned a home in the US for at least six months and you sell it, and the proceeds of the sale give you at least £62,500, that can count as having the savings for six months.
