Head coach Brian Ashton has started the process of cutting names from World Cup contention, with Olly Morgan, Fraser Waters, Shane Geraghty, Louis Deacon, Andy Hazell and Magnus Lund the first batch to be cut adrift.
Another 10 players will go - some, possibly next week - as Ashton builds towards revealing the 30 players entrusted with making England's Webb Ellis Trophy defence in France during September and October.
And second-row forward Borthwick, out of the England scene since last year's RBS 6 Nations, desperately wants to be in the mix.
He said: "In 2003, the (England) team was pretty much written in.
"There weren't that many places to be decided, whereas there is a different situation this time around.
"I am determined to make it, and I believe I am in the best physical condition I've ever been in.
"I am confident I can mix it with the best in the world in terms of my skill levels, and I am in great nick."
England will fine-tune their World Cup preparations by facing Wales and France (twice) on successive weekends next month, and Borthwick added: "I am just hoping that Brian gives me a chance in these August games.
"I missed out in our big success in 2003, so this World Cup is huge for me."