This is an US Export-Import Bank loan, not a presidential loan. Ex-Im actually makes money AND supports US industry. http://www.factcheck.org/2009/09/bogus-brazilian-oil-claims/
Ex-Im debt must be used to purchase US goods (equipment not services). Other bi-lateral lending agencies from other countries do the same thing to support their countries' exports. Picture this: as you are putting together a plan for funding your investment, you get bids for the equipment from different countries and you go visit all the bi-laterals and compare the cost of their debt. You also look at tax issues, exchange rates, etc. You put together the best deal-- eg highest ROI -- you can. Alternatively, let's say you are a US company bidding on the deal. You might include the cost of financing in your bid. So you visit Ex-Im and try to structure your bid so it will qualify for Ex-Im debt, which is cheaper than commercial lenders but definitely not cheaper than other bi-lateral agencies. Ex-Im expects to get paid back and is pretty conservative.
Sometimes, another country's lending agency will "buy" the project, offering such a sweet deal that the US companies can't even compete. They do this to support their industry; France comes to mind. Ex-Im Bank does not; it has traditionally been very conservative.
Petrobras has announced plans to invest $45 billion/year over the next five years, $12 billion sourced from outside the country. Looks like the US is trying hard to get a bigger share of the pie. We could use it.
US exports to Brazil: http://www.census.gov/foreign-trade/statistics/product/enduse/exports/c3510.html