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The most metal-poor stars (e.g. [Fe/H] $\leq-2.5$) are the ancient fossilsfrom the early assembly epoch of our Galaxy, very likely before the formationof the thick disc. Recent studies have shown that a non-negligible fraction ofthem have prograde planar orbits, which makes their origin a puzzle. It hasbeen suggested that a later-formed rotating bar could have driven these oldstars from the inner Galaxy outward, and transformed their orbits to be morerotation-dominated. However, it is not clear if this mechanism can explainthese stars as observed in the solar neighborhood. In this paper, we explorethe possibility of this scenario by tracing these stars backwards in anaxisymmetric Milky Way potential with a bar perturber. We integrate theirorbits backward for 6 Gyr under two bar models: one with a constant patternspeed and another one with a decelerating speed. Our experiments show that,under the constantly-rotating bar model, the stars of interest are littleaffected by the bar and cannot have been shepherded from a spheroidal innerMilky Way to their current orbits. In the extreme case of a rapidlydecelerating bar, some of the very metal-poor stars on planar and progradeorbits can be brought from the inner Milky Way, but $\sim90\%$ of them werenevertheless already rotation-dominated ($J_{\phi}$ $\geq$ 1000 km s$^{-1}$kpc) 6 Gyr ago. The chance of these stars having started with spheroid-likeorbits with small rotation ($J_{\phi}$ $\lesssim$ 600 km s$^{-1}$ kpc) is verylow ($<$ 3$\%$). We therefore conclude that, within the solar neighborhood, thebar is unlikely to have shepherded a significant fraction of inner Galaxyspheroid stars to produce the overdensity of stars on prograde, planar orbitsthat is observed today.

Could very low-metallicity stars with rotation-dominated orbits have been shepherded by the bar?