Jeffren, 26, was once regarded as one of the best talents in Spain after impressing in Barcelona's youth system before progressing to the first team at Camp Nou.
The Spain Under-21 international moved to Sporting in 2011 after falling out of favour at Barca, but has struggled for form and fitness in Portugal.
"On Tuesday or Wednesday I'll get to Portugal. I have two offers to present to the board. Yes, one of the offer is from [Rayo Vallecano]. The other is also from a Spanish team, but I'm not authorized to disclose the name," Brain Pugach told A Bola.
The identity of the other club in question remains unclear.