Context : We have entered an era of large spectroscopic surveys in which we can measure , through automated pipelines , the atmospheric parameters and chemical abundances for large numbers of stars .
Calibrating these survey pipelines using a set of ” benchmark stars ” in order to evaluate the accuracy and precision of the provided parameters and abundances is of utmost importance .
The recent proposed set of Gaia FGK benchmark stars of has up to five metal-poor stars but no recommended stars within -2.0 < [ Fe/H ] < -1.0 dex .
However , this metallicity regime is critical to calibrate properly .

Aims : In this paper , we aim to add candidate Gaia benchmark stars inside of this metal-poor gap .
We began with a sample of 21 metal-poor stars which was reduced to 10 stars by requiring accurate photometry and parallaxes , and high-resolution archival spectra .

Methods : The procedure used to determine the stellar parameters was similar to and for consistency .
The difference was to homogeneously determine the angular diameter and effective temperature ( \mathrm { T } _ { \mathrm { eff } } ) of all of our stars using the Infrared Flux Method utilizing multi-band photometry .
The surface gravity ( \log g ) was determined through fitting stellar evolutionary tracks .
The [ Fe/H ] was determined using four different spectroscopic methods fixing the \mathrm { T } _ { \mathrm { eff } } and \log g from the values determined independent of spectroscopy .

Results : We discuss , star-by-star , the quality of each parameter including how it compares to literature , how it compares to a spectroscopic run where all parameters are free , and whether { Fe \textsc { i } } ionisation-excitation balance is achieved .

Conclusions : From the 10 stars , we recommend a sample of five new metal-poor benchmark candidate stars which have consistent \mathrm { T } _ { \mathrm { eff } } , \log g , and [ Fe/H ] determined through several means .
These stars , which are within -1.3 < [ Fe/H ] < -1.0 , can be used for calibration and validation purpose of stellar parameter and abundance pipelines and should be of highest priority for future interferometric studies .